latex-dev (27feb21)

git-svn-id: svn://tug.org/texlive/trunk@57982 c570f23f-e606-0410-a88d-b1316a301751

133 files changed, 7056 insertions, 752 deletions

diff --git a/Master/texmf-dist/source/latex-dev/base/alltt.dtx b/Master/texmf-dist/source/latex-dev/base/alltt.dtx
index 0810cd73023..350229ab40f 100644
--- a/Master/texmf-dist/source/latex-dev/base/alltt.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/alltt.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -30,7 +30,7 @@
 %%
 %% File `alltt.dtx'.
 %% Copyright (C) 1987 by Leslie Lamport
-%% Copyright (C) 1994--2020 LaTeX3 project, Johannes Braams
+%% Copyright (C) 1994-2021 LaTeX Project, Johannes Braams
 %%                       all rights reserved.
 %%
 %<*dtx>
@@ -40,10 +40,11 @@
 %<package>\ProvidesPackage{alltt}
 %<driver>\ProvidesFile{alltt.drv}
 %\ProvidesFile{alltt.dtx}
-              [2020/11/23 v2.0g defines alltt environment]
+              [2021/01/29 v2.0g defines alltt environment]
 %
 %<*driver>
 \documentclass{ltxdoc}
+\usepackage{alltt}
 \begin{document}
 \providecommand{\Lenv}[1]{\textsf{#1}}
 \providecommand{\pkg}[1]{\texttt{#1}}
@@ -55,6 +56,8 @@
 %
 % \changes{v2.0g}{1997/06/16}{A few documentation fixes (PR 2520)}
 % \changes{v2.0d}{1995/04/02}{A few documentation fixes (PR 1517)}
+% \changes{v2.0g}{2021-01-29}{Added a warning about OT1 versus T1 font
+% encoding}
 %
 %  \GetFileInfo{alltt.dtx}
 %  \title{The \texttt{alltt} environment\thanks{This file
@@ -88,11 +91,19 @@
 %    extra blank line if you're not careful.
 %
 %   \item Insert a math formula.  Note that |$| just produces a dollar
-%   sign, so you'll have to type |\(...\)| or |\[...\]|.  Also, |^|
-%   and |_| just produce their characters; use |\sp| or |\sb| for
-%   super- and subscripts, as in |\(x\sp{2}\)|.
+%    sign, so you'll have to type |\(...\)| or |\[...\]|.  Also, |^|
+%    and |_| just produce their characters; use |\sp| or |\sb| for
+%    super- and subscripts, as in |\(x\sp{2}\)|.
 %   \end{itemize}
 %
+%    \textbf{NB} When you are using \textsf{OT1} encoded fonts you might
+%    be surprsied when you switch to italics, becuase those fonts have
+%    a different set of glyphs:
+%    \begin{alltt}
+%  The glyph at the position of the $ in a slanted font: \textsl{$}.
+%  The glyph at the position of the $ in an italic font: \textit{$}.
+%    \end{alltt}
+%
 %  \StopEventually{}
 %
 %  \section{The Implementation}
diff --git a/Master/texmf-dist/source/latex-dev/base/alltt.ins b/Master/texmf-dist/source/latex-dev/base/alltt.ins
index 817a00f3a68..7ce21032079 100644
--- a/Master/texmf-dist/source/latex-dev/base/alltt.ins
+++ b/Master/texmf-dist/source/latex-dev/base/alltt.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/classes.dtx b/Master/texmf-dist/source/latex-dev/base/classes.dtx
index c91b3381435..ffe04c620fa 100644
--- a/Master/texmf-dist/source/latex-dev/base/classes.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/classes.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -53,7 +53,7 @@
 %<*driver>
 \ProvidesFile{classes.drv}
 %</driver>
-              [2020/11/23 v1.4m
+              [2021/02/12 v1.4n
 %<article|report|book> Standard LaTeX document class]
 %<10pt|11pt|12pt>      Standard LaTeX file (size option)]
 %    \end{macrocode}
@@ -221,9 +221,9 @@
 %    file has version number \fileversion, last revised \filedate.}}
 %
 % \author{%
-% Copyright (C) 1992 by Leslie Lamport \and
-% Copyright (C) 1994-2020 by Frank Mittelbach \and Johannes Braams \and
-%                            \LaTeX3 Project Team
+% Copyright (C) 1992 by Leslie Lamport and
+% Copyright (C) 1994-2020 by Frank Mittelbach and Johannes Braams and
+%                            LaTeX Project Team
 % }
 % \date{\filedate}
 % \MaintainedByLaTeXTeam{latex}
@@ -2953,11 +2953,12 @@
 %    the labels of the various itemization levels: the symbols used are
 %    bullet, bold en-dash, centered asterisk and centred dot.
 %
+% \changes{v1.4n}{2021/06/11}{Drop incorrect space in \cs{labelitemiv} (gh/496)}
 %    \begin{macrocode}
 \newcommand\labelitemi  {\labelitemfont \textbullet}
 \newcommand\labelitemii {\labelitemfont \bfseries \textendash}
 \newcommand\labelitemiii{\labelitemfont \textasteriskcentered}
-\newcommand\labelitemiv{ \labelitemfont \textperiodcentered}
+\newcommand\labelitemiv {\labelitemfont \textperiodcentered}
 %    \end{macrocode}
 %
 % \begin{macro}{\labelitemfont}
@@ -2966,13 +2967,16 @@
 %    produced regardless of surrounding conditions.
 %
 % \changes{v1.4l}{2019/12/20}{Normalize label fonts}
-%    A possible alternative would be
+%    Possible alternatives would be, for example,
 %\begin{verbatim}
-%\renewcommand\labelitemfont{%
-%   \fontseries\seriesdefault
-%   \fontshape\shapedefault\selectfont}
+%  \renewcommand\labelitemfont
+%     {\normalfont\fontfamily{lmss}\selectfont}
+%  \renewcommand\labelitemfont
+%     {\rmfamily\normalshape}
 %\end{verbatim}
-%    which resets series and shape doesn't touch the family.
+%    the first would use symbols from Latin Modern Sans, the second
+%    would only allow changes in the font series so that an
+%    \texttt{itemize} in a bold context would produce bolder symbols.
 %    \begin{macrocode}
 \newcommand\labelitemfont{\normalfont}
 %    \end{macrocode}
diff --git a/Master/texmf-dist/source/latex-dev/base/classes.ins b/Master/texmf-dist/source/latex-dev/base/classes.ins
index b3f3e19fc40..be0dcaf8ff3 100644
--- a/Master/texmf-dist/source/latex-dev/base/classes.ins
+++ b/Master/texmf-dist/source/latex-dev/base/classes.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/cmextra.ins b/Master/texmf-dist/source/latex-dev/base/cmextra.ins
index f96b04221a7..c530e04d0bb 100644
--- a/Master/texmf-dist/source/latex-dev/base/cmextra.ins
+++ b/Master/texmf-dist/source/latex-dev/base/cmextra.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/cmfonts.fdd b/Master/texmf-dist/source/latex-dev/base/cmfonts.fdd
index 1eb318b0492..f991ee564ee 100644
--- a/Master/texmf-dist/source/latex-dev/base/cmfonts.fdd
+++ b/Master/texmf-dist/source/latex-dev/base/cmfonts.fdd
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright 1993-2019
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/cmfonts.ins b/Master/texmf-dist/source/latex-dev/base/cmfonts.ins
index 430abdd5f96..d54a325f42e 100644
--- a/Master/texmf-dist/source/latex-dev/base/cmfonts.ins
+++ b/Master/texmf-dist/source/latex-dev/base/cmfonts.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/doc.dtx b/Master/texmf-dist/source/latex-dev/base/doc.dtx
index c860a674382..c1a96948a89 100644
--- a/Master/texmf-dist/source/latex-dev/base/doc.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/doc.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/docstrip.dtx b/Master/texmf-dist/source/latex-dev/base/docstrip.dtx
index ea3a443c395..c7480988b44 100644
--- a/Master/texmf-dist/source/latex-dev/base/docstrip.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/docstrip.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -42,7 +42,7 @@
 %%                         Frank Mittelbach
 %% Copyright (C) 1995 Marcin Woli\'nski
 %% Copyright (C) 1996-1997 Mark Wooding, Marcin Woli\'nski
-%% Copyright (C) 1998-2020 LaTeX3 project and the above authors
+%% Copyright (C) 1998-2021 LaTeX Project and the above authors.
 %% All rights are reserved.
 %%
 %
@@ -789,7 +789,7 @@
 %
 % \section{Internal functions and variables}
 %
-%    An important consideration for \LaTeX3 development is separating
+%    An important consideration for \LaTeX\ development is separating
 %    out public and internal functions. Functions and variables which
 %    are private to one module should not be used or modified by any
 %    other module. As \TeX{} does not have any formal namespacing
diff --git a/Master/texmf-dist/source/latex-dev/base/docstrip.ins b/Master/texmf-dist/source/latex-dev/base/docstrip.ins
index edc75d8258c..e34281fc365 100644
--- a/Master/texmf-dist/source/latex-dev/base/docstrip.ins
+++ b/Master/texmf-dist/source/latex-dev/base/docstrip.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -53,7 +53,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ec.ins b/Master/texmf-dist/source/latex-dev/base/ec.ins
index ce702d8a27f..90b7b2e61f3 100644
--- a/Master/texmf-dist/source/latex-dev/base/ec.ins
+++ b/Master/texmf-dist/source/latex-dev/base/ec.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/exscale.dtx b/Master/texmf-dist/source/latex-dev/base/exscale.dtx
index b6f465443f5..ea67cb6fb72 100644
--- a/Master/texmf-dist/source/latex-dev/base/exscale.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/exscale.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/exscale.ins b/Master/texmf-dist/source/latex-dev/base/exscale.ins
index 8a22a7f9385..cfd2c535a77 100644
--- a/Master/texmf-dist/source/latex-dev/base/exscale.ins
+++ b/Master/texmf-dist/source/latex-dev/base/exscale.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/fix-cm.dtx b/Master/texmf-dist/source/latex-dev/base/fix-cm.dtx
index d844b65aa51..1be2e16cc09 100644
--- a/Master/texmf-dist/source/latex-dev/base/fix-cm.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/fix-cm.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/fix-cm.ins b/Master/texmf-dist/source/latex-dev/base/fix-cm.ins
index 840d5e408c2..95931970f47 100644
--- a/Master/texmf-dist/source/latex-dev/base/fix-cm.ins
+++ b/Master/texmf-dist/source/latex-dev/base/fix-cm.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/fontdef.dtx b/Master/texmf-dist/source/latex-dev/base/fontdef.dtx
index 6900a020744..581cfeb7895 100644
--- a/Master/texmf-dist/source/latex-dev/base/fontdef.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/fontdef.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -39,7 +39,7 @@
 %<driver, >\ProvidesFile{fontdef.drv}
 % \fi
 %          \ProvidesFile{fontdef.dtx}
-%<-latexrelease>           [2020/11/24 v3.0i LaTeX Kernel
+%<-latexrelease>           [2021/01/15 v3.0i LaTeX Kernel
 % \iftrue  (\else
 %<text,   >(Text
 %<math,   >(Math
@@ -227,7 +227,7 @@
 %    described in \texttt{ltoutenc.dtx}.
 %
 %    By convention, text  encoding specific declarations, including the
-%    declaration |\DeclareFontEncoding|, are kept in separate file of
+%    |\DeclareFontEncoding| declaration, are kept in separate file of
 %    the form \meta{enc}\texttt{enc.def}, e.g.~\texttt{ot1enc.def}. This
 %    allows other applications to make use of the declarations as
 %    well.
diff --git a/Master/texmf-dist/source/latex-dev/base/format.ins b/Master/texmf-dist/source/latex-dev/base/format.ins
index f872c31a3e4..9c90555b9f3 100644
--- a/Master/texmf-dist/source/latex-dev/base/format.ins
+++ b/Master/texmf-dist/source/latex-dev/base/format.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
@@ -88,8 +88,8 @@ reports for it can be opened at https://latex-project.org/bugs.html
 (but please observe conditions on bug reports sent to that address!)
 
 
-Copyright 2015
-The LaTeX3 Project and any individual authors listed elsewhere
+Copyright (C) 2015-2021
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
@@ -124,7 +124,7 @@ extension .ins) which are part of the distribution.
 This is a generated file.
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
@@ -166,6 +166,7 @@ the system are in the document `cfgguide.tex'.
 % we have the extensions as soon as possible.
           \from{ltexpl.dtx}{2ekernel}         % expl3-based extensions
           \from{ltdefns.dtx}{2ekernel}
+          \from{ltcmd.dtx}{2ekernel}          % Used to be xparse
           \from{lthooks.dtx}{2ekernel}        % L3 layer module
           \from{ltalloc.dtx}{2ekernel}
           \from{ltcntrl.dtx}{2ekernel}
@@ -233,13 +234,15 @@ the system are in the document `cfgguide.tex'.
 
 % hook management support
 
-\generate{\file{everyshi-ltx.sty}{\from{ltshipout.dtx}{everyshi-ltx}}} % emulating everyshi
 \generate{\file{atbegshi-ltx.sty}{\from{ltshipout.dtx}{atbegshi-ltx}}} % emulating atbegshi
 \generate{\file{atveryend-ltx.sty}{\from{ltfilehook.dtx}{atveryend-ltx}}} % emulating atveryend
 
 \generate{\file{structuredlog.sty}{\from{ltfilehook.dtx}{structuredlog}}}
 
 
+% hook managed para
+
+\generate{\file{ltpara.ltx}{\from{ltpara.dtx}{2ekernel}}}
 
 
 % luatex support (TeX part)
diff --git a/Master/texmf-dist/source/latex-dev/base/graphpap.dtx b/Master/texmf-dist/source/latex-dev/base/graphpap.dtx
index 0a89a25fe11..cc9f4da3cb1 100644
--- a/Master/texmf-dist/source/latex-dev/base/graphpap.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/graphpap.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/graphpap.ins b/Master/texmf-dist/source/latex-dev/base/graphpap.ins
index 9528f3dcdc5..65156ad9176 100644
--- a/Master/texmf-dist/source/latex-dev/base/graphpap.ins
+++ b/Master/texmf-dist/source/latex-dev/base/graphpap.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ifthen.dtx b/Master/texmf-dist/source/latex-dev/base/ifthen.dtx
index f07e4aa8f16..acb5cf19670 100644
--- a/Master/texmf-dist/source/latex-dev/base/ifthen.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ifthen.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -30,7 +30,7 @@
 %%
 %% File `ifthen.dtx'.
 %% Copyright (C) 1991 by Leslie Lamport
-%% Copyright (C) 1994-2001 LaTeX3 project, David Carlisle
+%% Copyright (C) 1994-2001 LaTeX project, David Carlisle
 %%                       all rights reserved.
 %%
 %
diff --git a/Master/texmf-dist/source/latex-dev/base/ifthen.ins b/Master/texmf-dist/source/latex-dev/base/ifthen.ins
index d589deaafca..42e1d3f5d93 100644
--- a/Master/texmf-dist/source/latex-dev/base/ifthen.ins
+++ b/Master/texmf-dist/source/latex-dev/base/ifthen.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/inputenc.dtx b/Master/texmf-dist/source/latex-dev/base/inputenc.dtx
index d8649c778df..1b8691d30fa 100644
--- a/Master/texmf-dist/source/latex-dev/base/inputenc.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/inputenc.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% LaTeX3 Project and any individual authors listed elsewhere
+% LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -283,7 +283,7 @@
 % with the |utf8| option.
 %
 % The |\DeclareUnicodeCharacter| takes UTF-8 code point as its first argument
-% (in form of a a hexadecimal number) and the definition that this maps to as
+% (in form of a hexadecimal number) and the definition that this maps to as
 % its second argument. For example, the code point |00E4| which is
 % ``LATIN SMALL LETTER A WITH DIAERESIS'' would be set up via:
 %\begin{verbatim}
@@ -410,7 +410,7 @@
 %<cp1252&!ansinew>  \ProvidesFile{cp1252.def}
 %<cp1250>  \ProvidesFile{cp1250.def}
 %<cp1257>  \ProvidesFile{cp1257.def}
-   [2020/11/26 v1.3d Input encoding file]
+   [2021/02/14 v1.3d Input encoding file]
 %<cp850>%%
 %<cp850>%% If you need a Euro symbol, try cp858 instead.
 %<cp850>%%
diff --git a/Master/texmf-dist/source/latex-dev/base/inputenc.ins b/Master/texmf-dist/source/latex-dev/base/inputenc.ins
index 19a8606e5d4..920a585bffc 100644
--- a/Master/texmf-dist/source/latex-dev/base/inputenc.ins
+++ b/Master/texmf-dist/source/latex-dev/base/inputenc.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/latex209.dtx b/Master/texmf-dist/source/latex-dev/base/latex209.dtx
index 183028fca77..bf92f8ef1e8 100644
--- a/Master/texmf-dist/source/latex-dev/base/latex209.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/latex209.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/latex209.ins b/Master/texmf-dist/source/latex-dev/base/latex209.ins
index 7c5197b9bd4..33ebc2488c4 100644
--- a/Master/texmf-dist/source/latex-dev/base/latex209.ins
+++ b/Master/texmf-dist/source/latex-dev/base/latex209.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/latexrelease.dtx b/Master/texmf-dist/source/latex-dev/base/latexrelease.dtx
index 19a1d0db806..cfcac4b3971 100644
--- a/Master/texmf-dist/source/latex-dev/base/latexrelease.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/latexrelease.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -40,7 +40,7 @@
 %<*!fixltx2e>
 % \fi
 %         \ProvidesFile{latexrelease.dtx}
-          [2020/12/06 v1.0k LaTeX release emulation and tests
+          [2021/01/23 v1.0l LaTeX release emulation and tests
               (including releases up to \latexreleaseversion)]
 % \iffalse
 %</!fixltx2e>
@@ -69,7 +69,7 @@
 % \title{The \Lpack{latexrelease} package\thanks{This file
 %         has version number \fileversion, last
 %         revised \filedate.}}
-% \author{The \LaTeX3 Project}
+% \author{The \LaTeX Project}
 % \date{\filedate}
 % \MaintainedByLaTeXTeam{latex}
 %  \maketitle
@@ -129,7 +129,6 @@
 % package has no information will generate a warning. Dates
 % earlier than 2015 will work but will roll back to some point in 2015
 % when the method was introduced.
-% |\IncludeInRelease| command is defined.
 % The |\requestedLaTeXdate| is set to the normalized date argument
 % so that package rollback defaults to the specified date.
 %
@@ -137,9 +136,6 @@
 % |current| This is the default behaviour, it does not change the
 % effective date of the format but does ensure that the
 % |\IncludeInRelease| command is defined.
-% the |\requestedLaTeXdate| is reset to 0 so that package rollback
-% does not use the implicit date.
-% |\IncludeInRelease| command is defined.
 % The |\requestedLaTeXdate| macro is reset to 0 so that package rollback
 % does not use the implicit date.
 %
@@ -147,11 +143,16 @@
 % |latest| sets the effective date of the format to the release date
 % of this file, so in an older format applies all patches currently
 % available.
-% |\IncludeInRelease| command is defined.
 % The |\requestedLaTeXdate| macro is reset to 0 so that package rollback
 % does not use the implicit date.
 % \end{itemize}
 %
+% In all cases, when the package is loaded, the |\sourceLaTeXdate| is
+% defined to be the numerical representation of |\fmtversion| before the
+% rollback/forward actually happens, so it is possible to test from which
+% was the original \LaTeX{} version before \Lpack{latexrelease} was loaded.
+% This is particularly useful when some code in a package has to be
+% redefined differently if rolling backwards in time or forwards.
 %
 % \section{Release Specific Code}
 %
@@ -388,6 +389,16 @@
 %
 % \section{Setup}
 %
+% \begin{macro}{\sourceLaTeXdate}
+%   \changes{v1.0l}{2021/01/23}{\cs{sourceLaTeXdate} added}
+%   Store the original \LaTeX{} format version
+%   as a number in the format |YYYYMMDD|:
+%    \begin{macrocode}
+\edef\sourceLaTeXdate{%
+  \expandafter\@parse@version\fmtversion//00\@nil}
+%    \end{macrocode}
+% \end{macro}
+%
 % \begin{macro}{\IncludeInRelease}
 % \begin{macro}{\EndIncludeInRelease}
 %    \begin{macrocode}
diff --git a/Master/texmf-dist/source/latex-dev/base/latexrelease.ins b/Master/texmf-dist/source/latex-dev/base/latexrelease.ins
index 141a677b48c..b4d0aef5677 100644
--- a/Master/texmf-dist/source/latex-dev/base/latexrelease.ins
+++ b/Master/texmf-dist/source/latex-dev/base/latexrelease.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
@@ -93,6 +93,7 @@ extension .ins) which are part of the distribution.
   \from{ltluatex.dtx}    {latexrelease}% empty 
   \from{ltexpl.dtx}      {latexrelease}% empty 
   \from{ltdefns.dtx}     {latexrelease}%
+  \from{ltcmd.dtx}       {latexrelease}%
   \from{lthooks.dtx}     {latexrelease}% empty  % L3 layer module
   \from{ltalloc.dtx}     {latexrelease}% empty
   \from{ltcntrl.dtx}     {latexrelease}% empty
diff --git a/Master/texmf-dist/source/latex-dev/base/latexsym.dtx b/Master/texmf-dist/source/latex-dev/base/latexsym.dtx
index c53dac62f0c..7a97aa4318c 100644
--- a/Master/texmf-dist/source/latex-dev/base/latexsym.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/latexsym.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/latexsym.ins b/Master/texmf-dist/source/latex-dev/base/latexsym.ins
index 620046ac9ba..902bbfc9e8e 100644
--- a/Master/texmf-dist/source/latex-dev/base/latexsym.ins
+++ b/Master/texmf-dist/source/latex-dev/base/latexsym.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
@@ -88,7 +88,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/letter.dtx b/Master/texmf-dist/source/latex-dev/base/letter.dtx
index faece887f86..3c7fe56ba15 100644
--- a/Master/texmf-dist/source/latex-dev/base/letter.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/letter.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -165,7 +165,7 @@
 % \changes{v1.3a}{2020/03/07}{merged changes to classes.dtx into letter.dtx}
 %
 % \iffalse
-% Copyright (C) 1994 LaTeX3 project, Frank Mittelbach
+% Copyright (C) 1994 LaTeX Project, Frank Mittelbach
 % and Rainer Sch\"opf, all rights reserved.
 % \fi
 %
diff --git a/Master/texmf-dist/source/latex-dev/base/letter.ins b/Master/texmf-dist/source/latex-dev/base/letter.ins
index 1c2b2f9f010..44777393eb6 100644
--- a/Master/texmf-dist/source/latex-dev/base/letter.ins
+++ b/Master/texmf-dist/source/latex-dev/base/letter.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltalloc.dtx b/Master/texmf-dist/source/latex-dev/base/ltalloc.dtx
index 3328c1f504d..59c492836f9 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltalloc.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltalloc.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltbibl.dtx b/Master/texmf-dist/source/latex-dev/base/ltbibl.dtx
index 7f5066542f3..0319342dd49 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltbibl.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltbibl.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltboxes.dtx b/Master/texmf-dist/source/latex-dev/base/ltboxes.dtx
index ec192293f10..8281b4b712b 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltboxes.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltboxes.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -33,7 +33,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltboxes.dtx}
-             [2020/12/05 v1.4a LaTeX Kernel (Box Commands)]
+             [2021/02/10 v1.4b LaTeX Kernel (Box Commands)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltboxes.dtx}
@@ -222,7 +222,7 @@
 % \changes{v1.0j}{1994/10/18}
 %         {stuff from ltpatch done}
 % \changes{v1.0p}{1994/11/09}
-%         {more colour changes\ldots}
+%         {more color changes\ldots}
 % \changes{v1.0q}{1994/11/17}
 %         {\cs{@tempa} to \cs{reserved@a}}
 % \changes{v1.0t}{1995/05/07}{Use \cs{hb@xt@}}
@@ -422,7 +422,7 @@
 %         {macro added}
 % \changes{v0.1a}{1993/12/03}
 %         {color support}
-% This macro is initially a no-op, but the colour package will redefine
+% This macro is initially a no-op, but the color package will redefine
 % it to insert a |\special|.
 %    \begin{macrocode}
 \let\set@color\relax
@@ -431,38 +431,66 @@
 %
 % \begin{macro}{\color@begingroup}
 % \changes{v1.0b}{1994/03/14}
-%         {macro added for colour support}
+%         {macro added for color support}
 % \begin{macro}{\color@endgroup}
 % \changes{v1.0b}{1994/03/14}
-%         {macro added for colour support}
+%         {macro added for color support}
 % \begin{macro}{\color@setgroup}
 % \changes{v1.0f}{1994/05/11}
-%         {macro added for colour support}
+%         {macro added for color support}
 % \begin{macro}{\normalcolor}
 % \changes{v1.0g}{1994/05/12}
-%         {macro added for colour support}
+%         {macro added for color support}
 % \begin{macro}{\color@hbox}
 % \changes{v1.0n}{1994/11/05}
-%         {macro added for colour support}
+%         {macro added for color support}
 % \begin{macro}{\color@vbox}
 % \changes{v1.0r}{1994/11/18}
-%         {macro added for colour support}
+%         {macro added for color support}
 % \begin{macro}{\color@endbox}
 % \changes{v1.0n}{1994/11/05}
-%         {macro added for colour support}
-% These macros are initially a no-op, but the colour package will
+%         {macro added for color support}
+% \changes{v1.4b}{2021/02/04}
+%         {Always add the color groups (gh/488)}
+% In the past these macros were initially no-ops, and the \pkg{color}
+% package redefined
 % redefine them to be |\begingroup|, |\endgroup|,
 % |\begingroup\set@color|,\\ |\hbox\bgroup\color@begingroup|,
 % |\color@endgroup\egroup|.
-% and \meta{set to main document colour} respectively.
+% and \meta{set to main document color} respectively.
+%
+% Nowadays we always set the group already in the kernel as this makes the
+% coding simpler.
 %    \begin{macrocode}
-\let\color@begingroup\relax
-\let\color@endgroup\relax
-\let\color@setgroup\relax
-\let\normalcolor\relax
-\let\color@hbox\relax
-\let\color@vbox\relax
-\let\color@endbox\relax
+%</2ekernel>
+%<*2ekernel|latexrelease>
+%<latexrelease>\IncludeInRelease{2021/05/01}%
+%<latexrelease>                 {\color@begingroup}{color group settings}%
+\let\color@begingroup\begingroup
+\def\color@endgroup{\endgraf\endgroup}
+\def\color@setgroup{\color@begingroup}        % changed further in color package
+\let\normalcolor\relax                        % remains untouched; only changed in a color package
+\def\color@hbox{\hbox\bgroup\color@begingroup}
+\def\color@vbox{\vbox\bgroup\color@begingroup}
+\def\color@endbox{\color@endgroup\egroup}
+%</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+%<latexrelease>\IncludeInRelease{0000/00/00}%
+%<latexrelease>                 {\color@begingroup}{color group settings}%
+%<latexrelease>
+%<latexrelease>\let\color@begingroup\relax
+%<latexrelease>\let\color@endgroup\relax
+%<latexrelease>\let\color@setgroup\relax
+%<latexrelease>\let\normalcolor\relax
+%<latexrelease>\let\color@hbox\relax
+%<latexrelease>\let\color@vbox\relax
+%<latexrelease>\let\color@endbox\relax
+%<latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%<*2ekernel>
 %    \end{macrocode}
 % \end{macro}
 % \end{macro}
@@ -1016,7 +1044,7 @@
 %
 % \begin{macro}{\@iiiminipage}
 % \changes{v1.0e}{1994/04/21}
-%     {Extra \cs{bgroup} for colour}
+%     {Extra \cs{bgroup} for color}
 % \changes{v1.0f}{1994/05/11}
 %         {Use new \cs{color@setgroup} concept.}
 % Internal form of |minipage|.
@@ -1054,11 +1082,11 @@
 %     {(RmS) replaced \cs{vskip}-\cs{lastskip} by \cs{unskip}
 %       (proposed by FMi)}
 % \changes{v1.0e}{1994/04/21}
-%     {Extra \cs{egroup} for colour}
+%     {Extra \cs{egroup} for color}
 % \changes{v1.0f}{1994/05/11}
 %         {Use new \cs{color@setgroup} concept.}
 % \changes{v1.0n}{1994/11/05}
-%     {Colour resetting for footnotes moved to here: as for main
+%     {Color resetting for footnotes moved to here: as for main
 %     page.}
 %    \begin{macrocode}
 \def\endminipage{%
@@ -1093,9 +1121,9 @@
 % Final |\strut| added 27 Mar 89, on suggestion by Don Hosek
 % \changes{LaTeX2.09}{1991/09/29}{(RmS) added \cs{reset@font}}
 % \changes{LaTeX2.09}{1992/11/26}{(RmS) added protection for \cs{edef}}
-% \changes{v0.1a}{1994/03/07}{Extra group for colour}
+% \changes{v0.1a}{1994/03/07}{Extra group for color}
 % \changes{v1.0e}{1994/04/21}
-%     {Extra \cs{endgraf} for colour}
+%     {Extra \cs{endgraf} for color}
 % \changes{v1.0f}{1994/05/11}
 %         {Use new \cs{color@setgroup} concept.}
 % \changes{v1.0f}{1994/05/11}
@@ -1103,11 +1131,17 @@
 % \changes{v1.0m}{1994/11/04}
 %         {Added \cs{protected@edef}. ASAJ.}
 % \changes{v1.0n}{1994/11/05}
-%     {Colour resetting for footnotes moved to endminipage: as for main
+%     {Color resetting for footnotes moved to endminipage: as for main
 %     page.}
 % \changes{v1.0o}{1994/11/05}
-%     {Colour groups restored here.}
+%     {Color groups restored here.}
+% \changes{v1.4b}{2021/02/10}
+%         {Explicitly run \cs{par} in support for paragraph tagging}
 %    \begin{macrocode}
+%</2ekernel>
+%<*2ekernel|latexrelease>
+%<latexrelease>\IncludeInRelease{2021/05/01}%
+%<latexrelease>                 {\@mpfootnotetext}{footnotetext tagging}%
 \long\def\@mpfootnotetext#1{%
   \global\setbox\@mpfootins\vbox{%
     \unvbox\@mpfootins
@@ -1119,7 +1153,31 @@
     \color@begingroup
       \@makefntext{%
         \rule\z@\footnotesep\ignorespaces#1\@finalstrut\strutbox}%
+    \par
     \color@endgroup}}
+%</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+%<latexrelease>\IncludeInRelease{0000/00/00}%
+%<latexrelease>                 {\@mpfootnotetext}{footnotetext tagging}%
+%<latexrelease>
+%<latexrelease>\long\def\@mpfootnotetext#1{%
+%<latexrelease>  \global\setbox\@mpfootins\vbox{%
+%<latexrelease>    \unvbox\@mpfootins
+%<latexrelease>    \reset@font\footnotesize
+%<latexrelease>    \hsize\columnwidth
+%<latexrelease>    \@parboxrestore
+%<latexrelease>    \protected@edef\@currentlabel
+%<latexrelease>         {\csname p@mpfootnote\endcsname\@thefnmark}%
+%<latexrelease>    \color@begingroup
+%<latexrelease>      \@makefntext{%
+%<latexrelease>        \rule\z@\footnotesep\ignorespaces#1\@finalstrut\strutbox}%
+%<latexrelease>    \color@endgroup}}
+%<latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%<*2ekernel>
 %    \end{macrocode}
 % \end{macro}
 %
diff --git a/Master/texmf-dist/source/latex-dev/base/ltclass.dtx b/Master/texmf-dist/source/latex-dev/base/ltclass.dtx
index 1400ec0a62d..26667cbeb1b 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltclass.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltclass.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -33,7 +33,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltclass.dtx}
-             [2020/12/17 v1.3v LaTeX Kernel (Class & Package Interface)]
+             [2021/02/18 v1.3x LaTeX Kernel (Class & Package Interface)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltclass.dtx}
@@ -712,6 +712,7 @@
 %   Path to the current file if explicitly given.  The auxiliary is
 %   needed here to insert a \cs{@empty} to prevent the loss of braces.
 %   \changes{v1.3u}{2020/11/20}{Macro added}
+%   \changes{v1.3w}{2021/01/21}{Add empty entry for latexrelease}
 %    \begin{macrocode}
 %</2ekernel>
 %<*2ekernel|latexrelease>
@@ -719,6 +720,7 @@
 %<latexrelease>\IncludeInRelease{2020/10/01}{\@kernel@currpathstack}%
 %<latexrelease>  {Add \@kernel@currpathstack}%
 \gdef\@kernel@currpathstack{}
+%<latexrelease>\g@addto@macro\@kernel@currpathstack{{}}
 \def\@p@pfilepath#1{%
   \gdef\@currpath{#1}\@p@pfilepath@aux\@empty}
 \def\@p@pfilepath@aux#1\@nil{%
@@ -1164,13 +1166,14 @@
 %
 % \begin{macro}{\PassOptionsToPackage}
 % \begin{macro}{\PassOptionsToClass}
-% If the package has been loaded, we check that it was first loaded with
-% the options.  Otherwise we add the option list to that of the package.
+%   If the package has been loaded, we check that it was first loaded with
+%   the options.  Otherwise we add the option list to that of the package.
 % \changes{v1.3t}{2020/10/18}{Drop path from \cs{input@path} (gh/414).}
+% \changes{v1.3x}{2021/02/18}{save raw option lists (gh/85)}
 %    \begin{macrocode}
 %</2ekernel>
-%<latexrelease>\IncludeInRelease{2020/10/01}{\@pass@ptions}
-%<latexrelease>  {Add file replacement in \@pass@ptions}%
+%<latexrelease>\IncludeInRelease{2021/05/01}%
+%<latexrelease>                 {\@pass@ptions}{Raw option lists}%
 %<*2ekernel|latexrelease>
 \def\@pass@ptions#1#2#3{%
   \@expl@@@filehook@set@curr@file@@nNN
@@ -1187,12 +1190,41 @@
 %    \begin{macrocode}
   \expandafter\let
     \csname opt@#3.#1\expandafter\endcsname
-    \csname opt@\reserved@a\endcsname}
+    \csname opt@\reserved@a\endcsname
+%    \end{macrocode}
+% Extend raw option list
+%    \begin{macrocode}
+    \@ifundefined{@raw@opt@#3.#1}%
+      {\expandafter\gdef\csname @raw@opt@#3.#1\endcsname{#2}}%
+      {\expandafter\g@addto@macro\csname @raw@opt@#3.#1\endcsname{,#2}}%
+}
 %</2ekernel|latexrelease>
 %<latexrelease>\EndIncludeInRelease
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+%<latexrelease>\IncludeInRelease{2020/10/01}{\@pass@ptions}
+%<latexrelease>  {Add file replacement in \@pass@ptions}%
+%<latexrelease>
+%<latexrelease>\def\@pass@ptions#1#2#3{%
+%<latexrelease>  \@expl@@@filehook@set@curr@file@@nNN
+%<latexrelease>    {\@expl@@@filehook@resolve@file@subst@@w #3.#1\@nil}%
+%<latexrelease>      \reserved@a\reserved@b
+%<latexrelease>  \@expl@@@filehook@clear@replacement@flag@@
+%<latexrelease>  \expandafter\xdef\csname opt@\reserved@a\endcsname{%
+%<latexrelease>    \@ifundefined{opt@\reserved@a}\@empty
+%<latexrelease>      {\csname opt@\reserved@a\endcsname,}%
+%<latexrelease>    \zap@space#2 \@empty}%
+%<latexrelease>  \expandafter\let
+%<latexrelease>    \csname opt@#3.#1\expandafter\endcsname
+%<latexrelease>    \csname opt@\reserved@a\endcsname}
+%<latexrelease>\EndIncludeInRelease
+%    \end{macrocode}
 %
+%    \begin{macrocode}
 %<latexrelease>\IncludeInRelease{0000/00/00}{\@pass@ptions}
 %<latexrelease>  {\@pass@ptions}%
+%<latexrelease>
 %<latexrelease>\def\@pass@ptions#1#2#3{%
 %<latexrelease>  \expandafter\xdef\csname opt@#3.#1\endcsname{%
 %<latexrelease>    \@ifundefined{opt@#3.#1}\@empty
@@ -1200,6 +1232,9 @@
 %<latexrelease>    \zap@space#2 \@empty}}
 %<latexrelease>\EndIncludeInRelease
 %<*2ekernel>
+%    \end{macrocode}
+%
+%    \begin{macrocode}
 \@onlypreamble\@pass@ptions
 %    \end{macrocode}
 %
@@ -1241,18 +1276,49 @@
 % \end{macro}
 %
 % \begin{macro}{\OptionNotUsed}
+% \changes{v1.3x}{2021/02/18}{filter out =value from unused option list (gh/85)}
+% \begin{macro}{\@remove@eq@value}
+% \changes{v1.3x}{2021/02/18}{macro added (gh/85)}
 % If we are in a class file, add |\CurrentOption| to the list of
 % unused options. Otherwise, in a package file do nothing.
 %    \begin{macrocode}
+%</2ekernel>
+%<latexrelease>\IncludeInRelease{2021/05/01}%
+%<latexrelease>                 {\OptionNotUsed}{filter unused option list}%
+%<*2ekernel|latexrelease>
+\def\@remove@eq@value#1=#2\@nil{#1}
+%    \end{macrocode}
+%
+%    \begin{macrocode}
 \def\OptionNotUsed{%
   \ifx\@currext\@clsextension
     \xdef\@unusedoptionlist{%
       \ifx\@unusedoptionlist\@empty\else\@unusedoptionlist,\fi
-      \CurrentOption}%
+      \expandafter\@remove@eq@value\CurrentOption=\@nil}%
   \fi}
+%</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%<latexrelease>\IncludeInRelease{0000/00/00}%
+%<latexrelease>                 {\OptionNotUsed}{filter unused option list}%
+%<latexrelease>\let\@remove@eq@value\@undefined
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+%<latexrelease>\def\OptionNotUsed{%
+%<latexrelease>  \ifx\@currext\@clsextension
+%<latexrelease>    \xdef\@unusedoptionlist{%
+%<latexrelease>      \ifx\@unusedoptionlist\@empty\else\@unusedoptionlist,\fi
+%<latexrelease>      \CurrentOption}%
+%<latexrelease>  \fi}
+%<latexrelease>\EndIncludeInRelease
+%<*2ekernel>
+%    \end{macrocode}
+%
+%    \begin{macrocode}
 \@onlypreamble\OptionNotUsed
 %    \end{macrocode}
 % \end{macro}
+% \end{macro}
 %
 % \begin{macro}{\default@ds}
 % The default option code.
@@ -1403,11 +1469,30 @@
 %         {Name changed from \cs{@executeoption}}
 % \changes{v1.0e}{1994/05/17}
 %         {Execute option after removing from list, not before}
+% \changes{v1.3x}{2021/02/18}{filter out =value from unused option list (gh/85)}
 %    \begin{macrocode}
+%</2ekernel>
+%<latexrelease>\IncludeInRelease{2021/05/01}%
+%<latexrelease>                 {\@use@ption}{filter unused option list}%
+%<*2ekernel|latexrelease>
 \def\@use@ption{%
-  \@expandtwoargs\@removeelement\CurrentOption
+  \@expandtwoargs\@removeelement
+     {\expandafter\@remove@eq@value\CurrentOption=\@nil}%
   \@unusedoptionlist\@unusedoptionlist
   \csname ds@\CurrentOption\endcsname}
+%</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%<latexrelease>\IncludeInRelease{0000/00/00}%
+%<latexrelease>                 {\@use@ption}{filter unused option list}%
+%<latexrelease>\def\@use@ption{%
+%<latexrelease>  \@expandtwoargs\@removeelement\CurrentOption
+%<latexrelease>  \@unusedoptionlist\@unusedoptionlist
+%<latexrelease>  \csname ds@\CurrentOption\endcsname}
+%<latexrelease>\EndIncludeInRelease
+%<*2ekernel>
+%    \end{macrocode}
+%
+%    \begin{macrocode}
 \@onlypreamble\@use@ption
 %    \end{macrocode}
 % \end{macro}
@@ -1721,15 +1806,23 @@
 %         {Prevent loss of brackets PR/3965}
 % \changes{v2.1b}{2016/11/09}
 %         {Improve \cs{ifx} tests PR/4497}
+% \changes{v1.3x}{2021/02/18}{save raw class option list (gh/85)}
 %    \begin{macrocode}
 %</2ekernel>
-%<latexrelease>\IncludeInRelease{2017/01/01}%
+%<latexrelease>\IncludeInRelease{2020/10/01}%
 %<latexrelease>        {\@fileswith@pti@ns}{ifx tests in \@fileswith@pti@ns}%
 %<*2ekernel|latexrelease>
 \def\@fileswith@pti@ns#1[#2]#3[#4]{%
   \ifx#1\@clsextension
     \ifx\@classoptionslist\relax
       \xdef\@classoptionslist{\zap@space#2 \@empty}%
+%    \end{macrocode}
+% Save raw class list.
+%    \begin{macrocode}
+      \gdef\@raw@classoptionslist{#2}%
+%    \end{macrocode}
+%
+%    \begin{macrocode}
       \def\reserved@a{%
         \@onefilewithoptions#3[{#2}][{#4}]#1%
         \@documentclasshook}%
@@ -1768,6 +1861,33 @@
   \fi
   \reserved@a}
 %</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%<latexrelease>\IncludeInRelease{2017/01/01}%
+%<latexrelease>        {\@fileswith@pti@ns}{ifx tests in \@fileswith@pti@ns}%
+%<latexrelease>\def\@fileswith@pti@ns#1[#2]#3[#4]{%
+%<latexrelease>  \ifx#1\@clsextension
+%<latexrelease>    \ifx\@classoptionslist\relax
+%<latexrelease>      \xdef\@classoptionslist{\zap@space#2 \@empty}%
+%<latexrelease>      \def\reserved@a{%
+%<latexrelease>        \@onefilewithoptions#3[{#2}][{#4}]#1%
+%<latexrelease>        \@documentclasshook}%
+%<latexrelease>    \else
+%<latexrelease>      \def\reserved@a{%
+%<latexrelease>        \@onefilewithoptions#3[{#2}][{#4}]#1}%
+%<latexrelease>    \fi
+%<latexrelease>  \else
+%<latexrelease>    \def\reserved@b##1,{%
+%<latexrelease>      \ifx\@nnil##1\relax\else
+%<latexrelease>        \ifx\@nnil##1\@nnil\else
+%<latexrelease>         \noexpand\@onefilewithoptions##1[{#2}][{#4}]%
+%<latexrelease>         \noexpand\@pkgextension
+%<latexrelease>        \fi
+%<latexrelease>        \expandafter\reserved@b
+%<latexrelease>      \fi}%
+%<latexrelease>      \edef\reserved@a{\zap@space#3 \@empty}%
+%<latexrelease>      \edef\reserved@a{\expandafter\reserved@b\reserved@a,\@nnil,}%
+%<latexrelease>  \fi
+%<latexrelease>  \reserved@a}
 %    \end{macrocode}
 %
 %    \begin{macrocode}
@@ -2640,7 +2760,8 @@
 % Text before the |\end|, write it with a warning.
 %    \begin{macrocode}
           \@latex@warning{Writing text `##1' before %
-             \string\end{\@currenvir}\MessageBreak as last line of \@curr@file}%
+            \string\end{\@currenvir}\MessageBreak
+            as last line of \@curr@file}%
         \immediate\write\reserved@c{##1}%
       \fi%
       \ifx\relax##2\relax%
@@ -2675,7 +2796,8 @@
 %</2ekernel|latexrelease>
 %<latexrelease>\EndIncludeInRelease
 %<latexrelease>\IncludeInRelease{2019/10/01}%
-%<latexrelease>                 {\filec@ntents}{Spaces in file names + optional arg}%
+%<latexrelease>    {\filec@ntents}{Spaces in file names + optional arg}%
+%<latexrelease>
 %<latexrelease>\def\filecontents{\@tempswatrue\@fileswtrue
 %<latexrelease>  \@ifnextchar[\filec@ntents@opt\filec@ntents
 %<latexrelease>}
@@ -2805,7 +2927,7 @@
 %<latexrelease>\endgroup%
 %<latexrelease>\EndIncludeInRelease
 %<latexrelease>\IncludeInRelease{0000/00/00}%
-%<latexrelease>                 {\filec@ntents}{Spaces in file names + optional arg}%
+%<latexrelease>    {\filec@ntents}{Spaces in file names + optional arg}%
 %<latexrelease>
 %<latexrelease>\let\filec@ntents@opt        \@undefined
 %<latexrelease>\let\filec@ntents@force      \@undefined
diff --git a/Master/texmf-dist/source/latex-dev/base/ltcmd.dtx b/Master/texmf-dist/source/latex-dev/base/ltcmd.dtx
new file mode 100644
index 00000000000..26ce75224fb
--- /dev/null
+++ b/Master/texmf-dist/source/latex-dev/base/ltcmd.dtx
@@ -0,0 +1,4041 @@
+% \iffalse meta-comment
+%
+% Copyright (C) 1999 Frank Mittelbach, Chris Rowley, David Carlisle
+% Copyright (C) 2004-2008 Frank Mittelbach, The LaTeX3 Project
+% Copyright (C) 2009-2021
+% The LaTeX Project and any individual authors listed elsewhere
+% in this file.
+%
+% This file is part of the LaTeX base system.
+% -------------------------------------------
+%
+% It may be distributed and/or modified under the
+% conditions of the LaTeX Project Public License, either version 1.3c
+% of this license or (at your option) any later version.
+% The latest version of this license is in
+%    https://www.latex-project.org/lppl.txt
+% and version 1.3c or later is part of all distributions of LaTeX
+% version 2008 or later.
+%
+% This file has the LPPL maintenance status "maintained".
+%
+% The list of all files belonging to the LaTeX base distribution is
+% given in the file `manifest.txt'. See also `legal.txt' for additional
+% information.
+%
+% The list of derived (unpacked) files belonging to the distribution
+% and covered by LPPL is defined by the unpacking scripts (with
+% extension .ins) which are part of the distribution.
+%
+% \fi
+%
+% \iffalse
+%
+%%% From File: ltcmd.dtx
+%
+%    \begin{macrocode}
+\def\ltcmdversion{v1.0a}
+\def\ltcmddate{2021/01/21}
+%    \end{macrocode}
+%
+%<*driver>
+% \fi
+\ProvidesFile{ltcmd.dtx}
+  [2020-11-20 v1.0 LaTeX Kernel (Document commands)]
+% \iffalse
+\documentclass{l3doc}
+\GetFileInfo{ltcmd.dtx}
+\title{\filename}
+\date{\filedate}
+\author{Frank Mittelbach, Chris Rowley, David Carlisle, \LaTeX{} Project Team}
+\begin{document}
+  \maketitle
+  \DocInput{ltcmd.dtx}
+\end{document}
+%</driver>
+% \fi
+%
+% \section{Creating document commands}
+%
+% \changes{v1.0}{2020-11-20}{Initial version derived from \texttt{xparse.dtx}}
+%
+% Document commands should be created using the tools provided by this module:
+% \cs{NewDocumentCommand}, etc.\@, in almost all cases. This allows clean
+% separation of document-level syntax from code-level interfaces. Users have
+% a need to create new document commands, and as such a significant amount of
+% documentation for \pkg{ltcmd} is provided as part of \texttt{usrguide3}. Here,
+% additional material aimed at programmers is provided
+%
+% \StopEventually{}
+%
+%    \begin{macrocode}
+%<@@=cmd>
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+%<*2ekernel>
+\message{document commands,}
+%</2ekernel>
+%    \end{macrocode}
+%
+% \pkg{ltcmd} code contains an |^^@| character, which usually has
+% catcode~15, so \cs{IncludeInRelease} will break when this code is
+% being skipped, so we'll save the catcode of |^^@| to restore later:
+%    \begin{macrocode}
+%<*2ekernel|latexrelease>
+%<latexrelease>\edef\@latexrelease@catcode@null{\the\catcode`\^^@ }
+%<latexrelease>\catcode`\^^@=12
+%<latexrelease>\IncludeInRelease{2021/05/01}%
+%<latexrelease>                 {\NewDocumentCommand}{Document commands}%
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\ExplSyntaxOn
+%    \end{macrocode}
+%
+% \subsection{Variables and constants}
+%
+% \begin{variable}{\l_@@_arg_spec_tl}
+%   Holds the argument specification after normalization of shorthands.
+%    \begin{macrocode}
+\tl_new:N \l_@@_arg_spec_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_args_tl}
+%   Token list variable for grabbed arguments.
+%    \begin{macrocode}
+\tl_new:N \l_@@_args_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_args_i_tl, \l_@@_args_ii_tl}
+%   Hold the modified arguments when dealing with default values or
+%   processors.
+%    \begin{macrocode}
+\tl_new:N \l_@@_args_i_tl
+\tl_new:N \l_@@_args_ii_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_current_arg_int}
+%   The number of the current argument being set up: this is used to
+%   make sure there are at most 9 arguments, then for creating the
+%   expandable auxiliary functions and knowing how many arguments the
+%   code function should take.
+%    \begin{macrocode}
+\int_new:N \l_@@_current_arg_int
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_defaults_bool, \l_@@_defaults_tl}
+%   The boolean indicates whether there are any argument with default
+%   value other than |-NoValue-|; the token list holds the code to
+%   determine these default values in terms of other arguments.
+%    \begin{macrocode}
+\bool_new:N \l_@@_defaults_bool
+\tl_new:N \l_@@_defaults_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_environment_bool}
+%   Generating environments uses the same mechanism as generating functions.
+%   However, full processing of arguments is always needed for environments,
+%   and so the function-generating code needs to know this.
+%   This variable is also used at run time to give correct error messages.
+%    \begin{macrocode}
+\bool_new:N \l_@@_environment_bool
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_environment_str}
+%   Name of the environment, used at definition time and at run time.
+%    \begin{macrocode}
+\str_new:N \l_@@_environment_str
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_expandable_bool}
+%   Used to indicate if an expandable command is begin generated, as this
+%   affects both the acceptable argument types and how they are implemented.
+%    \begin{macrocode}
+\bool_new:N \l_@@_expandable_bool
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_expandable_aux_name_tl}
+%   Used to create pretty-printing names for the auxiliaries: although the
+%   immediate definition does not vary, the full expansion does and so it
+%   does not count as a constant.
+%    \begin{macrocode}
+\tl_new:N \l_@@_expandable_aux_name_tl
+\tl_set:Nn \l_@@_expandable_aux_name_tl
+  {
+    \l_@@_function_tl \c_space_tl
+    ( arg~ \int_use:N \l_@@_current_arg_int )
+  }
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\g_@@_grabber_int}
+%   Used (in exceptional cases) to get unique names for grabbers used by
+%   expandable commands.
+%    \begin{macrocode}
+\int_new:N \g_@@_grabber_int
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_fn_tl}
+%   For passing the pre-formed name of the auxiliary to be used as the
+%   parsing function.
+%    \begin{macrocode}
+\tl_new:N \l_@@_fn_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_fn_code_tl}
+%   For passing the pre-formed name of the auxiliary that contains the
+%   actual code.
+%    \begin{macrocode}
+\tl_new:N \l_@@_fn_code_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_function_tl}
+%   Holds the control sequence name of the function currently being
+%   defined: used to avoid passing this as an argument and to avoid repeated
+%   use of \cs{cs_to_str:N}.
+%    \begin{macrocode}
+\tl_new:N \l_@@_function_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_grab_expandably_bool}
+%   When defining a non-expandable command, indicates whether the
+%   arguments can all safely be grabbed by expandable grabbers.  This is
+%   to support abuses of \pkg{xparse} that use protected functions
+%   inside csname constructions.
+%    \begin{macrocode}
+\bool_new:N \l_@@_grab_expandably_bool
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_obey_spaces_bool}
+%   For trailing optionals.
+%    \begin{macrocode}
+\bool_new:N \l_@@_obey_spaces_bool
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_last_delimiters_tl}
+%   Holds the delimiters (first tokens) of all optional arguments since
+%   the previous mandatory argument, to warn about cases where it would
+%   be impossible to omit optional arguments completely because the
+%   following mandatory argument has the same delimiter as one of the
+%   optional arguments.
+%    \begin{macrocode}
+\tl_new:N \l_@@_last_delimiters_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_long_bool}
+%   Used to indicate that an argument is long, on a per-argument basis.
+%    \begin{macrocode}
+\bool_new:N \l_@@_long_bool
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_m_args_int}
+%   The number of \texttt{m} arguments: if this is the same as the total
+%   number of arguments, then a short-cut can be taken in the creation of
+%   the grabber code.
+%    \begin{macrocode}
+\int_new:N \l_@@_m_args_int
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_prefixed_bool}
+%   When preparing the signature of non-expandable commands, indicates
+%   that the current argument is affected by a processor or by |+|
+%   (namely is long).
+%    \begin{macrocode}
+\bool_new:N \l_@@_prefixed_bool
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_process_all_tl, \l_@@_process_one_tl, \l_@@_process_some_bool}
+%   When preparing the signature, the processors that will be applied to
+%   a given argument are collected in \cs{l_@@_process_one_tl}, while
+%   \cs{l_@@_process_all_tl} contains processors for all arguments.  The
+%   boolean indicates whether there are any processors (to bypass the
+%   whole endeavour otherwise).
+%    \begin{macrocode}
+\tl_new:N \l_@@_process_all_tl
+\tl_new:N \l_@@_process_one_tl
+\bool_new:N \l_@@_process_some_bool
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_saved_args_tl}
+%   Stores \cs{l_@@_args_tl} to deal with space-trimming of
+%   \texttt{b}-type arguments.
+%    \begin{macrocode}
+\tl_new:N \l_@@_saved_args_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_signature_tl}
+%   Used when constructing the signature (code for argument grabbing) to
+%   hold what will become the implementation of the main function.
+%   When arguments are grabbed (at point of use of the command/environment),
+%   it also stores the code for grabbing the remaining arguments.
+%    \begin{macrocode}
+\tl_new:N \l_@@_signature_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}
+%   {\l_@@_some_obey_spaces_bool, \l_@@_some_long_bool, \l_@@_some_short_bool}
+%   These flags are set while normalizing the argument specification.
+%   The \texttt{obey_spaces} one is used to detect when |!| is used on
+%   an argument that is not a trailing optional argument.
+%   The other two are used to check whether all short arguments appear
+%   before long arguments: this is needed to grab arguments expandably.
+%   As soon as the first long argument is seen (other than
+%   \texttt{t}-type, whose long status is ignored) the
+%   \texttt{some_long} flag is set.  The \texttt{some_short} flag is
+%   used for expandable commands, to know whether to define a short
+%   auxiliary too.
+%    \begin{macrocode}
+\bool_new:N \l_@@_some_obey_spaces_bool
+\bool_new:N \l_@@_some_long_bool
+\bool_new:N \l_@@_some_short_bool
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_tmp_prop, \l_@@_tmpa_tl, \l_@@_tmpb_tl}
+% \begin{macro}{\@@_tmp:w}
+%   Scratch space.
+%    \begin{macrocode}
+\prop_new:N \l_@@_tmp_prop
+\tl_new:N \l_@@_tmpa_tl
+\tl_new:N \l_@@_tmpb_tl
+\cs_new_eq:NN \@@_tmp:w ?
+%    \end{macrocode}
+% \end{macro}
+% \end{variable}
+%
+%   With \pkg{xparse}, information about commands being (re)defined was
+%   switched off by default, unless the |log-declarations| package
+%   option was used, so here we'll switch that off as well.
+%    \begin{macrocode}
+\msg_redirect_module:nnn { LaTeX / ltcmd } { info } { none }
+%    \end{macrocode}
+%
+% \subsection{Declaring commands and environments}
+%
+% \begin{macro}{\@@_declare_cmd:Nnn, \@@_declare_expandable_cmd:Nnn}
+% \begin{macro}{\@@_declare_cmd_aux:Nnn}
+% \begin{macro}
+%   {\@@_declare_cmd_internal:Nnnn, \@@_declare_cmd_internal:cnxn}
+%   The main functions for creating commands set the appropriate flag then
+%   use the same internal code to do the definition.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd:Nnn
+  {
+    \bool_set_false:N \l_@@_expandable_bool
+    \@@_declare_cmd_aux:Nnn
+  }
+\cs_new_protected:Npn \@@_declare_expandable_cmd:Nnn
+  {
+    \bool_set_true:N \l_@@_expandable_bool
+    \@@_declare_cmd_aux:Nnn
+  }
+%    \end{macrocode}
+%  The first stage is to log information, both for the user in the log and
+%  for programmatic use in a property list of all declared commands.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd_aux:Nnn #1#2#3
+  {
+    \cs_if_exist:NTF #1
+      {
+        \__kernel_msg_info:nnxx { ltcmd } { redefine-command }
+          { \token_to_str:N #1 } { \tl_to_str:n {#2} }
+      }
+      {
+        \bool_lazy_or:nnT
+          { \cs_if_exist_p:c { \cs_to_str:N #1 ~ code } }
+          { \cs_if_exist_p:c { \cs_to_str:N #1 ~ defaults } }
+          {
+            \__kernel_msg_warning:nnx { ltcmd } { unsupported-let }
+              { \token_to_str:N #1 }
+          }
+        \__kernel_msg_info:nnxx { ltcmd } { define-command }
+          { \token_to_str:N #1 } { \tl_to_str:n {#2} }
+      }
+    \bool_set_false:N \l_@@_environment_bool
+    \@@_declare_cmd_internal:Nnnn #1 {#2} {#3} { }
+  }
+%    \end{macrocode}
+%   At definition time, the variable \cs{l_@@_fn_tl} is only used for error messages.
+%   The real business of defining a document command starts with setting up
+%   the appropriate name, then normalizing the argument specification to get rid of
+%   shorthands.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd_internal:Nnnn #1#2#3#4
+  {
+    \tl_set:Nx \l_@@_function_tl { \cs_to_str:N #1 }
+    \tl_set:Nx \l_@@_fn_tl
+      { \exp_not:c { \l_@@_function_tl \c_space_tl } }
+    \@@_normalize_arg_spec:n {#2}
+    \exp_args:No \@@_prepare_signature:n \l_@@_arg_spec_tl
+    \@@_declare_cmd_code:Nnn #1 {#2} {#3}
+    #4
+    \@@_break_point:n {#2}
+  }
+\cs_generate_variant:Nn \@@_declare_cmd_internal:Nnnn { cnx }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_break_point:n}
+%   A marker used to escape from creating a definition if necessary.
+%    \begin{macrocode}
+\cs_new_eq:NN \@@_break_point:n \use_none:n
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_declare_cmd_code:Nnn}
+% \begin{macro}
+%   {\@@_declare_cmd_code_aux:Nnn, \@@_declare_cmd_code_expandable:Nnn}
+%   The appropriate auxiliary is called.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd_code:Nnn
+  {
+    \bool_if:NTF \l_@@_grab_expandably_bool
+      { \@@_declare_cmd_code_expandable:Nnn }
+      { \@@_declare_cmd_code_aux:Nnn }
+   }
+%    \end{macrocode}
+%   Standard functions call \cs{@@_start:nNNnnn}, which receives the
+%   argument specification, an auxiliary used for
+%   grabbing arguments, an auxiliary containing the code, and then the
+%   signature, default arguments, and processors.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd_code_aux:Nnn #1#2#3
+  {
+    \cs_generate_from_arg_count:cNnn
+      { \l_@@_function_tl \c_space_tl code }
+      \cs_set_protected:Npn \l_@@_current_arg_int {#3}
+    \cs_set_protected_nopar:Npx #1
+      {
+        \bool_if:NTF \l_@@_environment_bool
+          {
+            \@@_start_env:nnnnn { \exp_not:n {#2} }
+              { \l_@@_environment_str }
+          }
+          {
+            \@@_start:nNNnnn { \exp_not:n {#2} }
+              \exp_not:c { \l_@@_function_tl \c_space_tl }
+              \exp_not:c { \l_@@_function_tl \c_space_tl code }
+          }
+          { \exp_not:o \l_@@_signature_tl }
+          {
+            \bool_if:NT \l_@@_defaults_bool
+              { \exp_not:o \l_@@_defaults_tl }
+          }
+          {
+            \bool_if:NT \l_@@_process_some_bool
+              { \exp_not:o \l_@@_process_all_tl }
+          }
+      }
+  }
+%    \end{macrocode}
+%   Expandable functions and functions whose arguments can be grabbed
+%   expandably call \cs{@@_start_expandable:nNNNNn}, which receives the
+%   argument specification, four auxiliaries (two for grabbing arguments, one for
+%   the code, and one for default arguments), and finally the signature.
+%   Non-expandable functions that take this branch should nevertheless
+%   be protected, as well as their \texttt{code} function.  They will
+%   only be expanded in contexts such as constructing a csname.
+%   The two grabbers (named after the function with one or two spaces)
+%   are needed when there are both short and long arguments; otherwise
+%   the same grabber is included twice in the definition.  If all
+%   arguments are long or all are short the (only) grabber is defined
+%   correspondingly to be long/short.  Otherwise two grabbers are
+%   defined, one long, one short.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_cmd_code_expandable:Nnn #1#2#3
+  {
+    \exp_args:Ncc \cs_generate_from_arg_count:NNnn
+      { \l_@@_function_tl \c_space_tl code }
+      { cs_set \bool_if:NF \l_@@_expandable_bool { _protected } :Npn }
+      \l_@@_current_arg_int {#3}
+    \bool_if:NT \l_@@_defaults_bool
+      {
+        \use:x
+          {
+            \cs_generate_from_arg_count:cNnn
+              { \l_@@_function_tl \c_space_tl defaults }
+              \cs_set:Npn \l_@@_current_arg_int
+              { \exp_not:o \l_@@_defaults_tl }
+          }
+      }
+    \bool_if:NTF \l_@@_expandable_bool
+      { \cs_set_nopar:Npx } { \cs_set_protected_nopar:Npx } #1
+      {
+        \exp_not:N \@@_start_expandable:nNNNNn
+          { \exp_not:n {#2} }
+          \exp_not:c { \l_@@_function_tl \c_space_tl }
+          \exp_not:c
+            {
+              \l_@@_function_tl \c_space_tl
+              \bool_if:NT \l_@@_some_short_bool
+                { \bool_if:NT \l_@@_some_long_bool { \c_space_tl } }
+            }
+          \exp_not:c { \l_@@_function_tl \c_space_tl code }
+          \bool_if:NTF \l_@@_defaults_bool
+            { \exp_not:c { \l_@@_function_tl \c_space_tl defaults } }
+            { ? }
+          { \exp_not:o \l_@@_signature_tl }
+      }
+    \bool_if:NTF \l_@@_some_long_bool
+      {
+        \bool_if:NT \l_@@_some_short_bool
+          {
+            \cs_set_nopar:cpx { \l_@@_function_tl \c_space_tl \c_space_tl }
+              ##1##2 { ##1 {##2} }
+          }
+        \cs_set:cpx
+      }
+      { \cs_set_nopar:cpx }
+          { \l_@@_function_tl \c_space_tl } ##1##2 { ##1 {##2} }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_declare_env:nnnn}
+% \begin{macro}{\@@_declare_env_internal:nnnn}
+%   The lead-off to creating an environment is much the same as that for
+%   creating a command: issue the appropriate message, store the argument
+%   specification then hand off to an internal function.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_env:nnnn #1#2
+  {
+    \str_set:Nx \l_@@_environment_str {#1}
+    \str_set:Nx \l_@@_environment_str
+      { \tl_trim_spaces:o { \l_@@_environment_str } }
+    \cs_if_exist:cTF { \l_@@_environment_str }
+      {
+        \__kernel_msg_info:nnxx { ltcmd } { redefine-environment }
+          { \l_@@_environment_str } { \tl_to_str:n {#2} }
+      }
+      {
+        \__kernel_msg_info:nnxx { ltcmd } { define-environment }
+          { \l_@@_environment_str } { \tl_to_str:n {#2} }
+      }
+    \bool_set_false:N \l_@@_expandable_bool
+    \bool_set_true:N \l_@@_environment_bool
+    \exp_args:NV \@@_declare_env_internal:nnnn
+      \l_@@_environment_str {#2}
+  }
+%    \end{macrocode}
+%   Creating a document environment requires a few more steps than creating
+%   a single command. In order to pass the arguments of the command to the
+%   end of the function, it is necessary to store the grabbed arguments.
+%   To do that, the function used at the end of the environment has to be
+%   redefined to contain the appropriate information. To minimize the amount
+%   of expansion at point of use, the code here is expanded now as well as
+%   when used.
+%   The last argument of \cs{@@_declare_cmd_internal:Nnnn} is only run
+%   if the definition succeeded.  In package mode this ensures that the
+%   original definition of the environment is not changed if the
+%   definition fails for any reason.  This also avoids an error when
+%   defining the \verb*|end aux | function when the user asks for more
+%   than $9$ arguments.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_declare_env_internal:nnnn #1#2#3#4
+  {
+    \@@_declare_cmd_internal:cnxn { environment~ #1 } {#2}
+      {
+        \cs_set_nopar:Npx \exp_not:c { environment~ #1 ~end~aux }
+          {
+            \exp_not:N \exp_not:N \exp_not:c { environment~ #1~end~aux~ }
+            \exp_not:n { \exp_not:o \l_@@_args_tl }
+          }
+        \exp_not:n {#3}
+      }
+      {
+        \cs_set_nopar:cpx { environment~ #1 ~end }
+          { \exp_not:c { environment~ #1 ~end~aux } }
+        \cs_generate_from_arg_count:cNnn
+          { environment~ #1 ~end~aux~ } \cs_set:Npn
+          \l_@@_current_arg_int {#4}
+        \cs_set_eq:cc {#1}       { environment~ #1 }
+        \cs_set_eq:cc { end #1 } { environment~ #1 ~end }
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Structure of \pkg{xparse} commands}
+%
+% \begin{macro}{\@@_start_env:nnnnn, \@@_start:nNNnnn}
+%   For error messages that occur during run-time when getting arguments
+%   of environments it is necessary to keep track of the environment
+%   name.  We begin non-expandable commands with a token equal to
+%   \cs{scan_stop:}, whose name gives a reasonable error message if the
+%   command is used inside a csname and protects against
+%   \texttt{f}-expansion.  This is useless for environments since
+%   \cs{begin} is already not expandable.  Both the command and
+%   environment codes start with \cs{group_align_safe_begin:}, then
+%   \cs{@@_run_code:} (used by both) does \cs{group_align_safe_end:}, so
+%   that delimited arguments may be grabbed in alignments if they
+%   contain and alignment tab token (see latex3/latex3/issues/839).
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_start_env:nnnnn #1#2
+  {
+    \conditionally@traceoff
+    \group_align_safe_begin:
+    \str_set:Nn \l_@@_environment_str {#2}
+    \bool_set_true:N \l_@@_environment_bool
+    \@@_start_aux:ccnnnn
+      { environment~ \l_@@_environment_str \c_space_tl }
+      { environment~ \l_@@_environment_str \c_space_tl code }
+      {#1}
+  }
+\cs_new_protected:Npx \@@_start:nNNnnn #1#2#3
+  {
+    \exp_not:c { xparse~function~is~not~expandable }
+    \exp_not:N \conditionally@traceoff
+    \exp_not:N \group_align_safe_begin:
+    \exp_not:n { \bool_set_false:N \l_@@_environment_bool }
+    \exp_not:N \@@_start_aux:NNnnnn
+    #2 #3 {#1}
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_start_aux:NNnnnn, \@@_start_aux:ccnnnn}
+%   This sets up a few variables to minimize the boilerplate code
+%   included in all \pkg{xparse}-defined commands.  It then runs the
+%   grabbers~|#4|.  Again, the argument specification |#1| is only for
+%   diagnostics.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_start_aux:NNnnnn #1#2#3#4#5#6
+  {
+    \tl_clear:N \l_@@_args_tl
+    \tl_set:Nn \l_@@_fn_tl {#1}
+    \tl_set:Nn \l_@@_fn_code_tl {#2}
+    \tl_set:Nn \l_@@_defaults_tl {#5}
+    \tl_set:Nn \l_@@_process_all_tl {#6}
+    #4 \@@_run_code:
+  }
+\cs_generate_variant:Nn \@@_start_aux:NNnnnn { cc }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_run_code:}
+%   After arguments are grabbed, this function is responsible for
+%   inserting default values, running processors, and finally doing
+%   \cs{group_align_safe_end:} as promised, and running the code.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_run_code:
+  {
+    \tl_if_empty:NF \l_@@_defaults_tl { \@@_defaults: }
+    \tl_if_empty:NF \l_@@_process_all_tl { \@@_args_process: }
+    \group_align_safe_end:
+    \conditionally@traceon
+    \exp_after:wN \l_@@_fn_code_tl \l_@@_args_tl
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_defaults:}
+% \begin{macro}{\@@_defaults_def:, \@@_defaults_def:nn, \@@_defaults_def:nnn}
+% \begin{macro}{\@@_defaults_aux:,  \@@_defaults_error:w}
+%   First construct \cs{@@_tmp:w} (see below) that will receive
+%   the arguments found so far and determine default values for any
+%   missing argument.  Then call it repeatedly until the set of
+%   arguments stabilizes.  Since that could lead to an infinite loop we
+%   only call it up to nine times, the maximal number needed for
+%   stabilization if there is a chain of arguments that depend on each
+%   other.  If that fails to stabilize raise an error.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_defaults:
+  {
+    \@@_defaults_def:
+    \tl_set_eq:NN \l_@@_args_i_tl \l_@@_args_tl
+    \@@_defaults_aux: \@@_defaults_aux: \@@_defaults_aux:
+    \@@_defaults_aux: \@@_defaults_aux: \@@_defaults_aux:
+    \@@_defaults_aux: \@@_defaults_aux: \@@_defaults_aux:
+    \@@_defaults_error:w
+    \q_recursion_stop
+    \tl_set_eq:NN \l_@@_args_tl \l_@@_args_i_tl
+  }
+\cs_new_protected:Npn \@@_defaults_aux:
+  {
+    \tl_set:Nx \l_@@_args_ii_tl
+      { \exp_after:wN \@@_tmp:w \l_@@_args_i_tl }
+    \tl_if_eq:NNT \l_@@_args_ii_tl \l_@@_args_i_tl
+      { \use_none_delimit_by_q_recursion_stop:w }
+    \tl_set_eq:NN \l_@@_args_i_tl \l_@@_args_ii_tl
+  }
+\cs_new_protected:Npn \@@_defaults_error:w \q_recursion_stop
+  {
+    \__kernel_msg_error:nnx { ltcmd } { loop-in-defaults }
+      { \@@_environment_or_command: }
+  }
+%    \end{macrocode}
+%   To construct \cs{@@_tmp:w}, first go through the arguments
+%   found and the corresponding defaults, building a token list with
+%   |{#|\meta{arg number}|}| for arguments found in the input (whose
+%   default will not be used) and otherwise
+%   |{|\cs{exp_not:n}\Arg{default}|}| for arguments whose default will
+%   be used.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_defaults_def:
+  {
+    \tl_clear:N \l_@@_tmpa_tl
+    \int_zero:N \l_@@_current_arg_int
+    \@@_tl_mapthread_function:NNN \l_@@_args_tl \l_@@_defaults_tl
+      \@@_defaults_def:nn
+    \cs_generate_from_arg_count:NNVo \@@_tmp:w \cs_set:Npn
+      \l_@@_current_arg_int \l_@@_tmpa_tl
+  }
+\cs_generate_variant:Nn \cs_generate_from_arg_count:NNnn { NNVo }
+\cs_new_protected:Npn \@@_defaults_def:nn
+  {
+    \int_incr:N \l_@@_current_arg_int
+    \exp_args:NV \@@_defaults_def:nnn \l_@@_current_arg_int
+  }
+\cs_new_protected:Npn \@@_defaults_def:nnn #1#2#3
+  {
+    \tl_put_right:Nx \l_@@_tmpa_tl
+      {
+        {
+          \exp_not:N \exp_not:n
+            {
+              \tl_if_novalue:nTF {#2}
+                { \exp_not:o {#3} }
+                { \exp_not:n { ## #1 } }
+            }
+        }
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_args_process:}
+% \begin{macro}{\@@_args_process_loop:nn, \@@_args_process_aux:n}
+%   Loop through arguments (stored in \cs{l_@@_args_tl}) and the
+%   corresponding processors (in \cs{l_@@_process_all_tl})
+%   simultaneously, apply all processors for each argument and store the
+%   result back into \cs{l_@@_args_tl}.  To allow processors to depend
+%   on other arguments, for every processor define a temporary auxiliary
+%   that receives all arguments \cs{l_@@_args_tl}.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_args_process:
+  {
+    \tl_clear:N \l_@@_args_ii_tl
+    \@@_tl_mapthread_function:NNN
+      \l_@@_args_tl
+      \l_@@_process_all_tl
+      \@@_args_process_loop:nn
+    \tl_set_eq:NN \l_@@_args_tl \l_@@_args_ii_tl
+  }
+\cs_new_protected:Npn \@@_args_process_loop:nn #1#2
+  {
+    \tl_set:Nn \ProcessedArgument {#1}
+    \tl_if_novalue:nF {#1}
+      { \tl_map_function:nN {#2} \@@_args_process_aux:n }
+    \tl_put_right:No \l_@@_args_ii_tl
+      { \exp_after:wN { \ProcessedArgument } }
+  }
+\cs_new_protected:Npn \@@_args_process_aux:n #1
+  {
+    \cs_generate_from_arg_count:NNnn \@@_tmp:w \cs_set:Npn
+      { \tl_count:N \l_@@_args_tl } {#1}
+    \exp_args:NNNo \exp_after:wN \@@_tmp:w \l_@@_args_tl
+      { \ProcessedArgument }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_start_expandable:nNNNNn}
+%   This is called for all expandable commands.  |#6| is the signature,
+%   responsible for grabbing arguments.  |#5| is used to determine
+%   default values (or is |?| if there are none).  |#4| is the code to run.
+%   |#2|~and~|#3| are functions (named after the command) that grab a single
+%   argument in the input stream (|#3|~is~short).  The argument specification |#1| is
+%   only used by diagnostic functions.  Same as for the non-expandable
+%   version, this starts with \cs{group_align_safe_begin:}, which
+%   expands to nothing, so may be safely used in an expandable context.
+%    \begin{macrocode}
+\cs_new:Npn \@@_start_expandable:nNNNNn #1#2#3#4#5#6
+  {
+    \group_align_safe_begin:
+    #6 \@@_end_expandable:NNw #5 #4 \q_@@ #2#3
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_end_expandable:NNw}
+% \begin{macro}[EXP]{\@@_end_expandable_aux:w}
+% \begin{macro}[EXP]{\@@_end_expandable_aux:nNNNN}
+% \begin{macro}[EXP]{\@@_end_expandable_defaults:nnnNNn}
+% \begin{macro}[EXP]{\@@_end_expandable_defaults:nnw}
+% \begin{macro}[EXP]{\@@_end_expandable_defaults:nw}
+%   Followed by a function |#1| to determine default values (or |?| if
+%   there are no defaults), the code
+%   |#2|, arguments that have been grabbed, then \cs{q_@@} and two generic
+%   grabbers.  The idea to find default values is similar to the
+%   non-expandable case but we cannot define an auxiliary function, so
+%   at every step in the loop we need to go through all arguments
+%   searching for which ones started out as |-NoValue-| and replacing
+%   these by the newly computed values.  In fact we need to keep track
+%   of three versions of all arguments: the original version, the
+%   previous version with default values, and the currently built
+%   version (first argument of \cs{@@_end_expandable_defaults:nnnNNn}).
+%    \begin{macrocode}
+\cs_new:Npn \@@_end_expandable:NNw #1#2
+  { \@@_end_expandable_aux:w #1#2 \prg_do_nothing: }
+\cs_new:Npn \@@_end_expandable_aux:w #1#2#3 \q_@@
+  { \exp_args:No \@@_end_expandable_aux:nNNNN {#3} #1 #2 }
+\cs_new:Npn \@@_end_expandable_aux:nNNNN #1#2#3#4#5
+  {
+    \token_if_eq_charcode:NNT ? #2 { \exp_after:wN \use_iv:nnnn }
+    \@@_end_expandable_defaults:nnnNNn {#1} { } {#1} #2#3
+      { } { } { } { } { } { } { } { } { } { }
+      {
+        \__kernel_msg_expandable_error:nnf
+          { ltcmd } { loop-in-defaults }
+          { \exp_args:Nf \tl_trim_spaces:n { \token_to_str:N #4 } }
+        \use_iv:nnnn
+      }
+    \q_stop
+  }
+\cs_new:Npn \@@_end_expandable_defaults:nnnNNn #1#2#3#4#5#6
+  {
+    #6
+    \str_if_eq:nnTF {#1} {#2}
+      { \use_i_delimit_by_q_stop:nw { \group_align_safe_end: #5 #1 } }
+      {
+        \exp_args:No \@@_tl_mapthread_function:nnN
+          { #4 #1 } {#3}
+          \@@_end_expandable_defaults:nnw
+        \@@_end_expandable_defaults:nnnNNn { } {#1} {#3} #4 #5
+      }
+  }
+\cs_new:Npn \@@_end_expandable_defaults:nnw #1#2
+  {
+    \tl_if_novalue:nTF {#2}
+      { \exp_args:No \@@_end_expandable_defaults:nw {#1} }
+      { \@@_end_expandable_defaults:nw {#2} }
+  }
+\cs_new:Npn \@@_end_expandable_defaults:nw
+    #1#2 \@@_end_expandable_defaults:nnnNNn #3
+  { #2 \@@_end_expandable_defaults:nnnNNn { #3 {#1} } }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Normalizing the argument specifications}
+%
+% The goal here is to expand aliases and check that the argument
+% specification is valid before the main parsing run.  If it is not
+% valid the entire set up is abandoned to avoid any strange internal
+% errors.  A function is provided for each argument type that will grab
+% any extra data items and call the loop function after performing the
+% following checks and tasks.
+% \begin{itemize}
+%   \item Check that each argument has the correct number of data items
+%     associated with it, and that where a single character is required,
+%     one has actually been supplied.
+%   \item Check that processors and the markers~|+| and~|!| are followed
+%     by an argument for which they make sense, and are not redundant.
+%   \item Check the absence of forbidden types for expandable commands,
+%     namely \texttt{G}/\texttt{v} always, and \texttt{l}/\texttt{u}
+%     after optional arguments (\pkg{xparse} may have inserted braces
+%     due to a failed search for an optional argument).
+%   \item Check that no optional argument is followed by a mandatory
+%     argument with the same delimiter, as otherwise the optional
+%     argument could never be omitted.
+%   \item Keep track in \cs{l_@@_some_long_bool} and
+%     \cs{l_@@_some_short_bool} of whether the command has some
+%     long/short arguments.
+%   \item Keep track in \cs{l_@@_grab_expandably_bool} of whether all
+%     arguments are \texttt{m}/\texttt{l}/\texttt{u} type and short
+%     arguments appear before long ones, in which case they can be
+%     grabbed expandably just as safely as they could be grabbed
+%     nonexpandably.  Regardless of that, arguments of expandable
+%     commands will be grabbed expandably and arguments of environments
+%     will not (because the list of arguments built by non-expandable
+%     grabbing is used to pass them to the end-environment code).
+% \end{itemize}
+% Further checks happen at the end of the loop:
+% \begin{itemize}
+% \item that there are at most $9$ arguments;
+% \item that an expandable command does not end with an optional
+%   argument (this case is detected by using the fact that
+%   \cs{l_@@_last_delimiters_tl} is cleared by every mandatory argument
+%   and filled by every optional argument).
+% \end{itemize}
+%
+% \begin{macro}{\@@_normalize_arg_spec:n}
+% \begin{macro}{\@@_normalize_arg_spec_loop:n}
+%   Loop through the argument specification, calling an auxiliary
+%   specific to each argument type.  If any argument is unknown stop the
+%   definition.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_normalize_arg_spec:n #1
+  {
+    \int_zero:N \l_@@_current_arg_int
+    \tl_clear:N \l_@@_last_delimiters_tl
+    \tl_clear:N \l_@@_arg_spec_tl
+    \bool_set_true:N \l_@@_grab_expandably_bool
+    \bool_set_false:N \l_@@_obey_spaces_bool
+    \bool_set_false:N \l_@@_long_bool
+    \bool_set_false:N \l_@@_some_obey_spaces_bool
+    \bool_set_false:N \l_@@_some_long_bool
+    \bool_set_false:N \l_@@_some_short_bool
+    \@@_normalize_arg_spec_loop:n #1
+      \q_recursion_tail \q_recursion_tail \q_recursion_tail \q_recursion_stop
+    \int_compare:nNnT \l_@@_current_arg_int > 9
+      {
+        \__kernel_msg_error:nnxx { ltcmd } { too-many-arguments }
+          { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+        \@@_bad_def:wn
+      }
+    \bool_if:NT \l_@@_expandable_bool
+      {
+        \tl_if_empty:NF \l_@@_last_delimiters_tl
+          {
+            \__kernel_msg_error:nnxx { ltcmd } { expandable-ending-optional }
+              { \iow_char:N \\ \l_@@_function_tl } { \tl_to_str:n {#1} }
+            \@@_bad_def:wn
+          }
+      }
+    \bool_if:NT \l_@@_expandable_bool
+      { \bool_set_true:N \l_@@_grab_expandably_bool }
+    \bool_if:NT \l_@@_environment_bool
+      { \bool_set_false:N \l_@@_grab_expandably_bool }
+  }
+\cs_new_protected:Npn \@@_normalize_arg_spec_loop:n #1
+  {
+    \quark_if_recursion_tail_stop:n {#1}
+    \int_incr:N \l_@@_current_arg_int
+    \cs_if_exist_use:cF { @@_normalize_type_ \tl_to_str:n {#1} :w }
+      {
+        \bool_lazy_any:nTF
+          {
+            { \str_if_eq_p:nn {#1} { G } }
+            { \str_if_eq_p:nn {#1} { g } }
+            { \str_if_eq_p:nn {#1} { l } }
+            { \str_if_eq_p:nn {#1} { u } }
+          }
+          {
+            \__kernel_msg_error:nnxx { ltcmd } { xparse-argument-type }
+              { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+          }
+          {
+            \__kernel_msg_error:nnxx { ltcmd } { unknown-argument-type }
+              { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+          }
+        \@@_bad_def:wn
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+%   {
+%     \@@_normalize_type_d:w,
+%     \@@_normalize_type_e:w,
+%     \@@_normalize_type_o:w,
+%     \@@_normalize_type_O:w,
+%     \@@_normalize_type_r:w,
+%     \@@_normalize_type_s:w,
+%   }
+%   These argument types are aliases of more general ones, for example
+%   with the default argument |-NoValue-|.  To easily insert that marker
+%   expanded in the definitions we call \cs{@@_tmp:w} with the argument
+%   |-NoValue-|.  For argument types that need additional data, check
+%   that the data is present (not \cs{q_recursion_tail}) before
+%   proceeding.
+%    \begin{macrocode}
+\cs_set_protected:Npn \@@_tmp:w #1
+  {
+    \cs_new_protected:Npn \@@_normalize_type_d:w ##1##2
+      {
+        \quark_if_recursion_tail_stop_do:nn {##2} { \@@_bad_arg_spec:wn }
+        \@@_normalize_type_D:w {##1} {##2} {#1}
+      }
+    \cs_new_protected:Npn \@@_normalize_type_e:w ##1
+      {
+        \quark_if_recursion_tail_stop_do:nn {##1} { \@@_bad_arg_spec:wn }
+        \@@_normalize_type_E:w {##1} { }
+      }
+    \cs_new_protected:Npn \@@_normalize_type_o:w
+      { \@@_normalize_type_D:w [ ] {#1} }
+    \cs_new_protected:Npn \@@_normalize_type_O:w
+      { \@@_normalize_type_D:w [ ] }
+    \cs_new_protected:Npn \@@_normalize_type_r:w ##1##2
+      {
+        \quark_if_recursion_tail_stop_do:nn {##2} { \@@_bad_arg_spec:wn }
+        \@@_normalize_type_R:w {##1} {##2} {#1}
+      }
+    \cs_new_protected:Npn \@@_normalize_type_s:w
+      { \@@_normalize_type_t:w * }
+  }
+\exp_args:No \@@_tmp:w { \c_novalue_tl }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+%   {
+%     \@@_normalize_type_>:w,
+%     \@@_normalize_type_+:w,
+%     \@@_normalize_type_!:w,
+%   }
+%   Check that these prefixes have arguments, namely that the next token
+%   is not \cs{q_recursion_tail}, and remember to leave it after the
+%   looping macro.  Processors are forbidden in expandable commands.
+%   If all is good, store the prefix in the cleaned up
+%   \cs{l_@@_arg_spec_tl}, and decrement the argument number as prefixes
+%   do not correspond to arguments.
+%    \begin{macrocode}
+\cs_new_protected:cpn { @@_normalize_type_>:w } #1#2
+  {
+    \quark_if_recursion_tail_stop_do:nn {#2} { \@@_bad_arg_spec:wn }
+    \bool_if:NT \l_@@_expandable_bool
+      {
+        \__kernel_msg_error:nnxx { ltcmd } { processor-in-expandable }
+          { \iow_char:N \\ \l_@@_function_tl } { \tl_to_str:n {#1} }
+        \@@_bad_def:wn
+      }
+    \tl_put_right:Nx \l_@@_arg_spec_tl { > { \tl_trim_spaces:n {#1} } }
+    \int_decr:N \l_@@_current_arg_int
+    \bool_set_false:N \l_@@_grab_expandably_bool
+    \@@_normalize_arg_spec_loop:n {#2}
+  }
+\cs_new_protected:cpn { @@_normalize_type_+:w } #1
+  {
+    \quark_if_recursion_tail_stop_do:nn {#1} { \@@_bad_arg_spec:wn }
+    \bool_if:NT \l_@@_long_bool
+      {
+        \__kernel_msg_error:nnxx { ltcmd } { two-markers }
+          { \@@_environment_or_command: } { + }
+        \@@_bad_def:wn
+      }
+    \bool_set_true:N \l_@@_long_bool
+    \int_decr:N \l_@@_current_arg_int
+    \@@_normalize_arg_spec_loop:n {#1}
+  }
+\cs_new_protected:cpn { @@_normalize_type_!:w } #1
+  {
+    \quark_if_recursion_tail_stop_do:nn {#1} { \@@_bad_arg_spec:wn }
+    \bool_if:NT \l_@@_obey_spaces_bool
+      {
+        \__kernel_msg_error:nnxx { ltcmd } { two-markers }
+          { \@@_environment_or_command: } { ! }
+        \@@_bad_def:wn
+      }
+    \bool_set_true:N \l_@@_obey_spaces_bool
+    \bool_set_true:N \l_@@_some_obey_spaces_bool
+    \int_decr:N \l_@@_current_arg_int
+    \@@_normalize_arg_spec_loop:n {#1}
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+%   {
+%     \@@_normalize_type_D:w,
+%     \@@_normalize_type_E:w,
+%     \@@_normalize_type_t:w,
+%   }
+% \begin{macro}{\@@_normalize_E_unique_check:w}
+%   Optional argument types.  Check that all required data is present
+%   (and consists of single characters if applicable) and check for
+%   forbidden types for expandable commands.  For \texttt{E}-type
+%   require that there is at least one embellishment, that each one is a
+%   single character, and that there aren't more optional arguments than
+%   embellishments; also remember that each embellishment counts as one
+%   argument for \cs{l_@@_current_arg_int}.  Then in each case
+%   store the data in \cs{l_@@_arg_spec_tl}, and
+%   for later checks store in \cs{l_@@_last_delimiters_tl} the tokens
+%   whose presence determines whether there is an optional argument (for
+%   braces store |{}|, seen later as an empty delimiter).
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_normalize_type_D:w #1#2#3
+  {
+    \quark_if_recursion_tail_stop_do:nn {#3} { \@@_bad_arg_spec:wn }
+    \@@_single_token_check:n {#1} \@@_allowed_token_check:N #1
+    \@@_single_token_check:n {#2}
+    \@@_add_arg_spec:n { D #1 #2 {#3} }
+    \tl_put_right:Nn \l_@@_last_delimiters_tl {#1}
+    \bool_set_false:N \l_@@_grab_expandably_bool
+    \@@_normalize_arg_spec_loop:n
+  }
+\cs_new_protected:Npn \@@_normalize_type_E:w #1#2
+  {
+    \quark_if_recursion_tail_stop_do:nn {#2} { \@@_bad_arg_spec:wn }
+    \tl_if_blank:nT {#1} { \@@_bad_arg_spec:wn }
+    \tl_map_function:nN {#1} \@@_single_token_check:n
+    \tl_map_function:nN {#1} \@@_allowed_token_check:N
+    \@@_normalize_E_unique_check:w #1 \q_nil \q_stop
+    \int_compare:nNnT { \tl_count:n {#2} } > { \tl_count:n {#1} }
+      { \@@_bad_arg_spec:wn }
+    \@@_add_arg_spec:n { E {#1} {#2} }
+    \tl_put_right:Nn \l_@@_last_delimiters_tl {#1}
+    \bool_set_false:N \l_@@_grab_expandably_bool
+    \int_add:Nn \l_@@_current_arg_int { \tl_count:n {#1} - 1 }
+    \@@_normalize_arg_spec_loop:n
+  }
+\cs_new_protected:Npn \@@_normalize_E_unique_check:w #1#2 \q_stop
+  {
+    \quark_if_nil:NF #1
+      {
+        \tl_if_in:nnT {#2} {#1} { \@@_bad_arg_spec:wn }
+        \@@_normalize_E_unique_check:w #2 \q_stop
+      }
+  }
+\cs_new_protected:Npn \@@_normalize_type_t:w #1
+  {
+    \quark_if_recursion_tail_stop_do:Nn #1 { \@@_bad_arg_spec:wn }
+    \@@_single_token_check:n {#1} \@@_allowed_token_check:N #1
+    \tl_put_right:Nx \l_@@_arg_spec_tl
+      {
+        \bool_if:NT \l_@@_obey_spaces_bool { ! }
+        t \exp_not:n {#1}
+      }
+    \tl_put_right:Nn \l_@@_last_delimiters_tl {#1}
+    \bool_set_false:N \l_@@_grab_expandably_bool
+    \bool_set_false:N \l_@@_obey_spaces_bool
+    \bool_set_false:N \l_@@_long_bool
+    \@@_normalize_arg_spec_loop:n
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+%   {
+%     \@@_normalize_type_m:w,
+%     \@@_normalize_type_R:w,
+%     \@@_normalize_type_v:w
+%   }
+%   Mandatory arguments.  First check the required data is present,
+%   consists of single characters where applicable, and that the argument
+%   type is allowed for expandable commands if applicable.  For the
+%   \texttt{m} and \texttt{R} argument types check that they do not
+%   follow some optional argument with that delimiter as otherwise the
+%   optional argument could not be omitted.  Then save data in
+%   \cs{l_@@_arg_spec_tl}, count the mandatory argument, and empty the
+%   list of last delimiters.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_normalize_type_m:w
+  {
+    \@@_delimiter_check:nnn { } { m } { \iow_char:N \{ }
+    \@@_add_arg_spec_mandatory:n { m }
+    \@@_normalize_arg_spec_loop:n
+  }
+\cs_new_protected:Npn \@@_normalize_type_R:w #1#2#3
+  {
+    \quark_if_recursion_tail_stop_do:nn {#3} { \@@_bad_arg_spec:wn }
+    \@@_single_token_check:n {#1} \@@_allowed_token_check:N #1
+    \@@_single_token_check:n {#2}
+    \@@_delimiter_check:nnn {#1} { R/r } { \tl_to_str:n {#1} }
+    \bool_set_false:N \l_@@_grab_expandably_bool
+    \@@_add_arg_spec_mandatory:n { R #1 #2 {#3} }
+    \@@_normalize_arg_spec_loop:n
+  }
+\cs_new_protected:Npn \@@_normalize_type_v:w
+  {
+    \@@_normalize_check_gv:N v
+    \@@_add_arg_spec_mandatory:n { v }
+    \@@_normalize_arg_spec_loop:n
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_normalize_type_b:w}
+%   This argument type is not allowed for commands.  This is only
+%   allowed at the end of the argument specification, hence we check
+%   that |#1| is the end.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_normalize_type_b:w #1
+  {
+    \bool_if:NF \l_@@_environment_bool
+      {
+        \__kernel_msg_error:nnxx
+          { ltcmd } { invalid-command-arg }
+          { \@@_environment_or_command: } { b }
+        \@@_bad_def:wn
+      }
+    \tl_clear:N \l_@@_last_delimiters_tl
+    \@@_add_arg_spec:n { b }
+    \quark_if_recursion_tail_stop:n {#1}
+    \__kernel_msg_error:nnxx { ltcmd } { arg-after-body }
+      { \@@_environment_or_command: }
+      { \tl_to_str:n {#1} }
+    \@@_bad_def:wn
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_single_token_check:n}
+%   Checks that the argument is a single (non-space) token (possibly
+%   surrounded by spaces), and aborts the definition otherwise.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_single_token_check:n #1
+  {
+    \tl_trim_spaces_apply:nN {#1} \tl_if_single_token:nF
+      {
+        \__kernel_msg_error:nnxx { ltcmd } { not-single-token }
+          { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+        \@@_bad_def:wn
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_allowed_token_check:N}
+%   Some tokens are now allowed as delimiters for some argument types,
+%   notably implicit begin/end-group tokens (|\bgroup|/|\egroup|).
+%   The major problem with these tokens is that for |\peek_...| functions,
+%   a literal~|{|$_1$. is virtually indistinguishable from a |\bgroup| or
+%   other token which was |\let| to a~|{|$_1$, and the same goes
+%   for~|}|$_2$.  All other tokens can be easily distingushed from their
+%   implicit counterparts by grabbing them and looking at the string
+%   length (see \cs{@@_token_if_cs:NTF}), but for begin/end group tokens
+%   that is not possible without the risk of mistakenly grabbing the
+%   entire brace group (potentially leading to a~\texttt{!~Runaway argument}
+%   error) or trying to grab a |}|$_2$, leading to
+%   an~\verb|! Argument of \dots has an extra }| error.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_allowed_token_check:N #1
+  {
+    \token_if_eq_meaning:NNTF #1 \c_group_begin_token
+        { \use:n }
+        {
+          \token_if_eq_meaning:NNTF #1 \c_group_end_token
+            { \use:n }
+            { \use_none:n }
+        }
+      {
+        \__kernel_msg_error:nnxxx
+          { ltcmd } { forbidden-implicit-group-token }
+          { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+          {
+            \token_if_eq_meaning:NNTF #1 \c_group_begin_token
+              { begin } { end }
+          }
+        \@@_bad_def:wn
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_normalize_check_gv:N, \@@_normalize_check_lu:N}
+%   Called for arguments that are always forbidden, or forbidden after
+%   an optional argument, for expandable commands.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_normalize_check_gv:N #1
+  {
+    \bool_if:NT \l_@@_expandable_bool
+      {
+        \__kernel_msg_error:nnxx
+          { ltcmd } { invalid-expandable-argument-type }
+          { \iow_char:N \\ \l_@@_function_tl } { \tl_to_str:n {#1} }
+        \@@_bad_def:wn
+      }
+    \bool_set_false:N \l_@@_grab_expandably_bool
+  }
+\cs_new_protected:Npn \@@_normalize_check_lu:N #1
+  {
+    \bool_if:NT \l_@@_expandable_bool
+      {
+        \tl_if_empty:NF \l_@@_last_delimiters_tl
+          {
+            \__kernel_msg_error:nnxx
+              { ltcmd } { invalid-after-optional-expandably }
+              { \iow_char:N \\ \l_@@_function_tl } { \tl_to_str:n {#1} }
+            \@@_bad_def:wn
+          }
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_delimiter_check:nnn}
+%   Called for \texttt{m} and \texttt{R} arguments.  Checks that the
+%   leading token does not coincide with the token denoting the presence
+%   of a previous optional argument.  Instead of dealing with braces for
+%   the \texttt{m}-type we use an empty delimiter to denote that case.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_delimiter_check:nnn #1#2#3
+  {
+    \tl_map_inline:Nn \l_@@_last_delimiters_tl
+      {
+        \tl_if_eq:nnT {##1} {#1}
+          {
+            \__kernel_msg_warning:nnxx { ltcmd } { optional-mandatory }
+              {#2} {#3}
+          }
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_bad_arg_spec:wn, \@@_bad_def:wn}
+%   If the argument specification is wrong, this provides an escape from
+%   the entire definition process.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_bad_arg_spec:wn #1 \@@_break_point:n #2
+  {
+    \__kernel_msg_error:nnxx { ltcmd } { bad-arg-spec }
+      { \@@_environment_or_command: } { \tl_to_str:n {#2} }
+  }
+\cs_new_protected:Npn \@@_bad_def:wn #1 \@@_break_point:n #2 { }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_arg_spec:n, \@@_add_arg_spec_mandatory:n}
+%   When adding an argument to the argument specification, set the
+%   \texttt{some_long} or \texttt{some_short} booleans as appropriate
+%   and clear the booleans keeping track of |+| and |!| markers.
+%   Before that, test for a short argument following some long
+%   arguments: this is forbidden for expandable commands and prevents
+%   grabbing arguments expandably.
+%
+%   For mandatory arguments do some more work, in particular complain if
+%   they were preceeded by~|!|.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_arg_spec:n #1
+  {
+    \bool_lazy_and:nnT
+      { ! \l_@@_long_bool }
+      { \l_@@_some_long_bool }
+      {
+        \bool_if:NT \l_@@_expandable_bool
+          {
+            \__kernel_msg_error:nnx { ltcmd } { inconsistent-long }
+              { \iow_char:N \\ \l_@@_function_tl }
+            \@@_bad_def:wn
+          }
+        \bool_set_false:N \l_@@_grab_expandably_bool
+      }
+    \bool_if:NTF \l_@@_long_bool
+      { \bool_set_true:N \l_@@_some_long_bool }
+      { \bool_set_true:N \l_@@_some_short_bool }
+    \tl_put_right:Nx \l_@@_arg_spec_tl
+      {
+        \bool_if:NT \l_@@_long_bool { + }
+        \bool_if:NT \l_@@_obey_spaces_bool { ! }
+        \exp_not:n {#1}
+      }
+    \bool_set_false:N \l_@@_long_bool
+    \bool_set_false:N \l_@@_obey_spaces_bool
+  }
+\cs_new_protected:Npn \@@_add_arg_spec_mandatory:n #1
+  {
+    \bool_if:NT \l_@@_some_obey_spaces_bool
+      {
+        \__kernel_msg_error:nnxx { ltcmd } { non-trailing-obey-spaces }
+          { \@@_environment_or_command: } { \tl_to_str:n {#1} }
+        \@@_bad_def:wn
+      }
+    \tl_clear:N \l_@@_last_delimiters_tl
+    \@@_add_arg_spec:n {#1}
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \subsection{Preparing the signature: general mechanism}
+%
+% \begin{macro}{\@@_prepare_signature:n}
+% \begin{macro}{\@@_prepare_signature:N}
+% \begin{macro}{\@@_prepare_signature_bypass:N}
+%   Actually creating the signature uses the same loop approach as
+%   normalizing the signature. There are first a number of variables which need
+%   to be set to track what is going on. Many of these variables are unused
+%   when defining expandable commands.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_prepare_signature:n #1
+  {
+    \int_zero:N \l_@@_current_arg_int
+    \bool_set_false:N \l_@@_long_bool
+    \bool_set_false:N \l_@@_obey_spaces_bool
+    \int_zero:N \l_@@_m_args_int
+    \bool_set_false:N \l_@@_defaults_bool
+    \tl_clear:N \l_@@_defaults_tl
+    \tl_clear:N \l_@@_process_all_tl
+    \tl_clear:N \l_@@_process_one_tl
+    \bool_set_false:N \l_@@_process_some_bool
+    \tl_clear:N \l_@@_signature_tl
+    \@@_prepare_signature:N #1 \q_recursion_tail \q_recursion_stop
+    \bool_if:NF \l_@@_expandable_bool { \@@_flush_m_args: }
+  }
+%    \end{macrocode}
+%  The main looping function does not take an argument, but carries out the
+%  reset on the processor boolean. This is split off from the rest of the
+%  process so that when actually setting up processors the flag-reset can
+%  be bypassed.
+%
+%  For each known argument type there is an appropriate function to actually
+%  do the addition to the signature. These are separate for expandable and
+%  standard functions, as the approaches are different.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_prepare_signature:N
+  {
+    \bool_set_false:N \l_@@_prefixed_bool
+    \@@_prepare_signature_bypass:N
+  }
+\cs_new_protected:Npn \@@_prepare_signature_bypass:N #1
+  {
+    \quark_if_recursion_tail_stop:N #1
+    \use:c
+      {
+         @@_add
+         \bool_if:NT \l_@@_grab_expandably_bool { _expandable }
+         _type_  \token_to_str:N #1 :w
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Setting up a standard signature}
+%
+% Each argument-adding function appends to the signature a grabber (and
+% for some types, the delimiters or default value), except the one for
+% \texttt{m} arguments.  These are collected and added to the signature
+% all at once by \cs{@@_flush_m_args:}, called for every other argument
+% type.  All of the functions then call the loop function
+% \cs{@@_prepare_signature:N}.  Default values of arguments are
+% collected by \cs{@@_add_default:n} rather than being stored with the
+% argument; this function and \cs{@@_add_default:} are also responsible
+% for keeping track of \cs{l_@@_current_arg_int}.
+%
+% \begin{macro}{\@@_add_type_+:w}
+%   Making the next argument long means setting the flag. The \texttt{m}
+%   arguments are recorded here as
+%   this has to be done for every case where there is then a long argument.
+%    \begin{macrocode}
+\cs_new_protected:cpn { @@_add_type_+:w }
+  {
+    \@@_flush_m_args:
+    \bool_set_true:N \l_@@_long_bool
+    \bool_set_true:N \l_@@_prefixed_bool
+    \@@_prepare_signature_bypass:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_!:w}
+%   Much the same for controlling trailing optional arguments.
+%    \begin{macrocode}
+\cs_new_protected:cpn { @@_add_type_!:w }
+  {
+    \@@_flush_m_args:
+    \bool_set_true:N \l_@@_obey_spaces_bool
+    \bool_set_true:N \l_@@_prefixed_bool
+    \@@_prepare_signature_bypass:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_>:w}
+%   When a processor is found, the processor code is stored.  It will be
+%   used by \cs{@@_args_process:} once arguments are all found. Here too
+%   the loop calls \cs{@@_prepare_signature_bypass:N} rather than
+%   \cs{@@_prepare_signature:N} so that the flag is not reset.
+%    \begin{macrocode}
+\cs_new_protected:cpn { @@_add_type_>:w } #1
+  {
+    \@@_flush_m_args:
+    \bool_set_true:N \l_@@_prefixed_bool
+    \bool_set_true:N \l_@@_process_some_bool
+    \tl_put_left:Nn \l_@@_process_one_tl { {#1} }
+    \@@_prepare_signature_bypass:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_b:w}
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_b:w
+  {
+    \@@_flush_m_args:
+    \@@_add_default:
+    \@@_add_grabber:N b
+    \@@_prepare_signature:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_D:w}
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_D:w #1#2#3
+  {
+    \@@_flush_m_args:
+    \@@_add_default:n {#3}
+    \@@_add_grabber:N D
+    \tl_put_right:Nn \l_@@_signature_tl { #1 #2 }
+    \@@_prepare_signature:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_E:w}
+%   The \texttt{E}-type argument needs a special handling of default
+%   values.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_E:w #1#2
+  {
+    \@@_flush_m_args:
+    \@@_add_default_E:nn {#1} {#2}
+    \@@_add_grabber:N E
+    \tl_put_right:Nn \l_@@_signature_tl { {#1} }
+    \@@_prepare_signature:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_m:w}
+%   The \texttt{m} type is special as short arguments which are not
+%   post-processed are simply counted at this stage. Thus there is a check
+%   to see if either of these cases apply. If so, a one-argument grabber
+%   is added to the signature. On the other hand, if a standard short
+%   argument is required it is simply counted at this stage, to be
+%   added later using \cs{@@_flush_m_args:}.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_m:w
+  {
+    \@@_add_default:
+    \bool_if:NTF \l_@@_prefixed_bool
+      { \@@_add_grabber:N m }
+      { \int_incr:N \l_@@_m_args_int }
+    \@@_prepare_signature:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_R:w}
+%   The \texttt{R}-type argument is very similar to the \texttt{D}-type.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_R:w #1#2#3
+  {
+    \@@_flush_m_args:
+    \@@_add_default:n {#3}
+    \@@_add_grabber:N R
+    \tl_put_right:Nn \l_@@_signature_tl { #1 #2 }
+    \@@_prepare_signature:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_t:w}
+%   Setting up a \texttt{t} argument means collecting one token for the test,
+%   and adding it along with the grabber to the signature.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_t:w #1
+  {
+    \@@_flush_m_args:
+    \@@_add_default:
+    \@@_add_grabber:N t
+    \tl_put_right:Nn \l_@@_signature_tl {#1}
+    \@@_prepare_signature:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_type_v:w}
+%   At this stage, the \texttt{v} argument is identical to \texttt{l}
+%   except that since the grabber may fail to read a verbatim argument
+%   we need a default value.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_type_v:w
+  {
+    \@@_flush_m_args:
+    \exp_args:No \@@_add_default:n \c_novalue_tl
+    \@@_add_grabber:N v
+    \@@_prepare_signature:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_flush_m_args:}
+%   As \texttt{m} arguments are simply counted, there is a need to add
+%   them to the token register in a block. As this function can only
+%   be called if something other than \texttt{m} turns up, the flag can
+%   be switched here.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_flush_m_args:
+  {
+    \int_compare:nNnT \l_@@_m_args_int > 0
+      {
+        \tl_put_right:Nx \l_@@_signature_tl
+          { \exp_not:c { @@_grab_m_ \int_use:N \l_@@_m_args_int :w } }
+        \tl_put_right:Nx \l_@@_process_all_tl
+          { \prg_replicate:nn { \l_@@_m_args_int } { { } } }
+      }
+    \int_zero:N \l_@@_m_args_int
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_grabber:N}
+%   To keep the various checks needed in one place, adding the grabber
+%   to the signature is done here.  The only questions are whether the
+%   grabber should be long or not, and whether to obey spaces.  The
+%   \cs{l_@@_obey_spaces_bool} boolean can only be \texttt{true} for
+%   trailing optional arguments.  In that case spaces will not be
+%   ignored when looking for that optional argument.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_grabber:N #1
+  {
+    \tl_put_right:Nx \l_@@_signature_tl
+      {
+        \exp_not:c
+          {
+            @@_grab_ #1
+            \bool_if:NT \l_@@_long_bool { _long }
+            \bool_if:NT \l_@@_obey_spaces_bool { _obey_spaces }
+            :w
+          }
+      }
+    \bool_set_false:N \l_@@_long_bool
+    \bool_set_false:N \l_@@_obey_spaces_bool
+    \tl_put_right:Nx \l_@@_process_all_tl
+      { { \exp_not:o \l_@@_process_one_tl } }
+    \tl_clear:N \l_@@_process_one_tl
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_default:n, \@@_add_default:, \@@_add_default_E:nn}
+%   Store the default value of an argument, or rather code that gives
+%   that default value (it may involve other arguments).  This is
+%   \cs{c_novalue_tl} for arguments with no actual default or with
+%   default |-NoValue-|; and (in a brace group) \cs{prg_do_nothing:}
+%   followed by a default value for others.  For \texttt{E}-type
+%   arguments, pad the defaults |#2| with some \cs{c_novalue_tl}
+%   until there are as many as embellishments~|#1|.  These functions are
+%   also used when defining expandable commands.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_default:n #1
+  {
+    \tl_if_novalue:nTF {#1}
+      { \@@_add_default: }
+      {
+        \int_incr:N \l_@@_current_arg_int
+        \bool_set_true:N \l_@@_defaults_bool
+        \tl_put_right:Nn \l_@@_defaults_tl { { \prg_do_nothing: #1 } }
+      }
+  }
+\cs_new_protected:Npn \@@_add_default:
+  {
+    \int_incr:N \l_@@_current_arg_int
+    \tl_put_right:Nn \l_@@_defaults_tl { \c_novalue_tl }
+  }
+\cs_new_protected:Npn \@@_add_default_E:nn #1#2
+  {
+    \tl_map_function:nN {#2} \@@_add_default:n
+    \prg_replicate:nn
+      { \tl_count:n {#1} - \tl_count:n {#2} }
+      { \@@_add_default: }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \subsection{Setting up expandable types}
+%
+% The approach here is not dissimilar to that for standard types, but fewer types
+% are supported. There is
+% also a need to define the per-function auxiliaries: this is done here, while
+% the general grabbers are dealt with later.
+%
+% \begin{macro}{\@@_add_expandable_type_+:w}
+%   We have already checked that short arguments are before long
+%   arguments, so \cs{l_@@_long_bool} only changes from \texttt{false}
+%   to \texttt{true} once (and there is no need to reset it after each
+%   argument).  Also knock back the argument count because |+| is not an
+%   argument.  Continue the loop.
+%    \begin{macrocode}
+\cs_new_protected:cpn { @@_add_expandable_type_+:w }
+  {
+    \bool_set_true:N \l_@@_long_bool
+    \@@_prepare_signature:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_type_D:w}
+% \begin{macro}{\@@_add_expandable_type_D_aux:NNNn}
+% \begin{macro}{\@@_add_expandable_type_D_aux:NNN}
+% \begin{macro}{\@@_add_expandable_type_D_aux:NN}
+%   The set up for \texttt{D}-type arguments involves constructing a
+%   rather complex auxiliary which is used
+%   repeatedly when grabbing. There is an auxiliary here so that the
+%   \texttt{R}-type can share code readily: |#1| is |D| or~|R|.
+%   The |_aux:NN| auxiliary is needed if the two delimiting tokens are
+%   identical: in contrast to the non-expandable route, the grabber here
+%   has to act differently for this case.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_type_D:w
+  { \@@_add_expandable_type_D_aux:NNNn D }
+\cs_new_protected:Npn \@@_add_expandable_type_D_aux:NNNn #1#2#3#4
+  {
+    \@@_add_default:n {#4}
+    \tl_if_eq:nnTF {#2} {#3}
+      { \@@_add_expandable_type_D_aux:NN #1 #2 }
+      { \@@_add_expandable_type_D_aux:NNN #1 #2 #3 }
+    \@@_prepare_signature:N
+  }
+\cs_new_protected:Npn \@@_add_expandable_type_D_aux:NNN #1#2#3
+  {
+    \bool_if:NTF \l_@@_long_bool
+      { \cs_set:cpx }
+      { \cs_set_nopar:cpx }
+      { \l_@@_expandable_aux_name_tl } ##1 ##2 #2 ##3 \q_@@ ##4 #3
+      { ##1 {##2} {##3} {##4} }
+    \@@_add_expandable_grabber:nn {#1}
+      {
+        \exp_not:c  { \l_@@_expandable_aux_name_tl }
+        \exp_not:n { #2 #3 }
+      }
+  }
+\cs_new_protected:Npn \@@_add_expandable_type_D_aux:NN #1#2
+  {
+    \bool_if:NTF \l_@@_long_bool
+      { \cs_set:cpx }
+      { \cs_set_nopar:cpx }
+      { \l_@@_expandable_aux_name_tl } ##1 #2 ##2 #2
+      { ##1 {##2} }
+    \@@_add_expandable_grabber:nn { #1_alt }
+      {
+        \exp_not:c  { \l_@@_expandable_aux_name_tl }
+        \exp_not:n {#2}
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_type_E:w}
+% \begin{macro}{\@@_add_expandable_type_E_aux:n}
+%   For each embellishment, use \cs{@@_get_grabber:NN} to obtain an
+%   auxiliary delimited by that token and store a pair constituted of
+%   the auxiliary and the token in \cs{l_@@_tmpb_tl}, before appending
+%   the whole set of these pairs to the signature, and an equal number
+%   of |-NoValue-| markers (regardless of the default values of
+%   arguments).  Set the current argument appropriately.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_type_E:w #1#2
+  {
+    \@@_add_default_E:nn {#1} {#2}
+    \tl_clear:N \l_@@_tmpb_tl
+    \tl_map_function:nN {#1} \@@_add_expandable_type_E_aux:n
+    \@@_add_expandable_grabber:nn
+      { E \bool_if:NT \l_@@_long_bool { _long } }
+      {
+        { \exp_not:o \l_@@_tmpb_tl }
+        {
+          \prg_replicate:nn { \tl_count:n {#1} }
+            { { \c_novalue_tl } }
+        }
+      }
+    \@@_prepare_signature:N
+  }
+\cs_new_protected:Npn \@@_add_expandable_type_E_aux:n #1
+  {
+    \@@_get_grabber:NN #1 \l_@@_tmpa_tl
+    \tl_put_right:Nx \l_@@_tmpb_tl
+      { \exp_not:o \l_@@_tmpa_tl \exp_not:N #1 }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_type_m:w}
+%   Unlike the standard case, when working expandably each argument is always
+%   grabbed separately.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_type_m:w
+  {
+    \@@_add_default:
+    \@@_add_expandable_grabber:nn
+      { m \bool_if:NT \l_@@_long_bool { _long } } { }
+    \@@_prepare_signature:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_type_R:w}
+%   The \texttt{R}-type is very similar to the \texttt{D}-type
+%   argument, and so the same internals are used.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_type_R:w
+  { \@@_add_expandable_type_D_aux:NNNn R }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_type_t:w}
+%   An auxiliary delimited by |#1| is built now.  It will be used to
+%   test for the presence of that token.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_type_t:w #1
+  {
+    \@@_add_default:
+    \@@_get_grabber:NN #1 \l_@@_tmpa_tl
+    \@@_add_expandable_grabber:nn { t }
+      {
+        \exp_not:o \l_@@_tmpa_tl
+        \exp_not:N #1
+      }
+    \@@_prepare_signature:N
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_expandable_grabber:nn}
+%   This is called for all arguments to place the right grabber in the
+%   signature.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_expandable_grabber:nn #1#2
+  {
+    \tl_put_right:Nx \l_@@_signature_tl
+      { \exp_not:c { @@_expandable_grab_ #1 :w } #2 }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_get_grabber:NN}
+% \begin{macro}{\@@_get_grabber_auxi:NN}
+% \begin{macro}{\@@_get_grabber_auxii:NN}
+%   Given a token |#1|, defines an expandable function delimited by that
+%   token and stores it in the token list~|#2|.  The function is named
+%   after the token, unless that function name is already taken by some
+%   other grabber (this can happen in the rare case where delimiters
+%   with different category codes are used in the same document): in
+%   that case use a global counter to get a unique name.  Since the
+%   grabbers are not named after \pkg{xparse} commands they should not
+%   be used to get material from the input stream.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_get_grabber:NN #1#2
+  {
+    \cs_set:Npn \@@_tmp:w ##1 #1 {##1}
+    \exp_args:Nc \@@_get_grabber_auxi:NN
+      { @@_grabber_ \token_to_str:N #1 :w } #2
+  }
+\cs_new_protected:Npn \@@_get_grabber_auxi:NN #1#2
+  {
+    \cs_if_eq:NNTF \@@_tmp:w #1
+      { \tl_set:Nn #2 {#1} }
+      {
+        \cs_if_exist:NTF #1
+          {
+            \int_gincr:N \g_@@_grabber_int
+            \exp_args:Nc \@@_get_grabber_auxi:NN
+              {
+                @@_grabber_
+                - \int_use:N \g_@@_grabber_int :w
+              }
+              #2
+          }
+          { \@@_get_grabber_auxii:NN #1 #2 }
+      }
+  }
+\cs_new_protected:Npn \@@_get_grabber_auxii:NN #1#2
+  {
+    \cs_set_eq:NN #1 \@@_tmp:w
+    \tl_set:Nn #2 {#1}
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Grabbing arguments}
+%
+% All of the grabbers follow the same basic pattern. The initial
+% function stores in \cs{l_@@_signature_tl} the code to grab further
+% arguments, defines (the function in) \cs{l_@@_fn_tl} that will grab
+% the argument, and calls it.
+%
+% Defining \cs{l_@@_fn_tl} means determining whether to use
+% \cs{cs_set:Npn} or \cs{cs_set_nopar:Npn}, and for optional arguments
+% whether to skip spaces. Once the argument is found, \cs{l_@@_fn_tl}
+% calls \cs{@@_add_arg:n}, responsible for calling processors and
+% grabbing further arguments.
+%
+% \begin{macro}
+%   {
+%     \@@_grab_b:w,
+%     \@@_grab_b_long:w,
+%     \@@_grab_b_obey_spaces:w,
+%     \@@_grab_b_long_obey_spaces:w,
+%     \@@_grab_b_aux:NNw,
+%     \@@_grab_b_end:Nw
+%   }
+%   This uses the well-tested code of \texttt{D}-type arguments,
+%   skipping the peeking step because the \texttt{b}-type argument is
+%   always present, and adding a cleanup stage at the end by hijacking
+%   the signature.  The clean-up consists of properly
+%   dealing with \cs{l_@@_args_tl} and also putting back the \cs{end}
+%   that served as an end-delimiter: this \cs{end} receives the
+%   environment name as its argument and is run normally.  The
+%   \texttt{D}-type code stores the argument found (body of the
+%   environment) as a brace group in \cs{l_@@_args_tl} and depending on
+%   the presence of a prefix~|!| we trim spaces or not before adding
+%   this braced argument into the saved \cs{l_@@_args_tl}.
+%   The strange \verb*|\begin | control sequence is there for display
+%     purposes only: it has to look like |\begin| in the terminal but
+%       not to delimited arguments.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_b:w
+  { \@@_grab_b_aux:NNw \cs_set_protected_nopar:Npn \tl_trim_spaces:n }
+\cs_new_protected:Npn \@@_grab_b_long:w
+  { \@@_grab_b_aux:NNw \cs_set_protected:Npn \tl_trim_spaces:n }
+\cs_new_protected:Npn \@@_grab_b_obey_spaces:w
+  { \@@_grab_b_aux:NNw \cs_set_protected_nopar:Npn \exp_not:n }
+\cs_new_protected:Npn \@@_grab_b_long_obey_spaces:w
+  { \@@_grab_b_aux:NNw \cs_set_protected:Npn \exp_not:n }
+\cs_new_protected:Npn \@@_grab_b_aux:NNw #1#2#3 \@@_run_code:
+  {
+    \@@_grab_D_aux:NNnN \begin \end {#3} #1
+    \tl_put_left:Nn \l_@@_signature_tl { \@@_grab_b_end:Nw #2 }
+    \tl_set_eq:NN \l_@@_saved_args_tl \l_@@_args_tl
+    \tl_clear:N \l_@@_args_tl
+    \exp_args:Nc \l_@@_fn_tl { begin ~ }
+  }
+\cs_new_protected:Npn \@@_grab_b_end:Nw #1#2 \@@_run_code:
+  {
+    \tl_set:Nx \l_@@_args_tl
+      {
+        \exp_not:V \l_@@_saved_args_tl
+        { \exp_after:wN #1 \l_@@_args_tl }
+      }
+    #2
+    \@@_run_code:
+    \end
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_D:w}
+% \begin{macro}{\@@_grab_D_long:w}
+% \begin{macro}{\@@_grab_D_obey_spaces:w}
+% \begin{macro}{\@@_grab_D_long_obey_spaces:w}
+%   The generic delimited argument grabber. The auxiliary function does
+%   a peek test before calling \cs{@@_grab_D_call:Nw}, so that the
+%   optional nature of the argument works as expected.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_D:w #1#2#3 \@@_run_code:
+  {
+    \@@_grab_D_aux:NNnNN #1 #2 {#3} \cs_set_protected_nopar:Npn
+      \@@_peek_nonspace_remove:NTF
+  }
+\cs_new_protected:Npn \@@_grab_D_long:w #1#2#3 \@@_run_code:
+  {
+    \@@_grab_D_aux:NNnNN #1 #2 {#3} \cs_set_protected:Npn
+      \@@_peek_nonspace_remove:NTF
+  }
+\cs_new_protected:Npn \@@_grab_D_obey_spaces:w #1#2#3 \@@_run_code:
+  {
+    \@@_grab_D_aux:NNnNN #1 #2 {#3} \cs_set_protected_nopar:Npn
+      \@@_peek_meaning_remove:NTF
+  }
+\cs_new_protected:Npn \@@_grab_D_long_obey_spaces:w #1#2#3 \@@_run_code:
+  {
+    \@@_grab_D_aux:NNnNN #1 #2 {#3} \cs_set_protected:Npn
+      \@@_peek_meaning_remove:NTF
+  }
+%    \end{macrocode}
+% \begin{macro}{\@@_grab_D_aux:NNnNN}
+% \begin{macro}{\@@_grab_D_aux:NNnN}
+%   This is a bit complicated. The idea is that, in order to check for
+%   nested optional argument tokens (\texttt{[[...]]} and so on) the
+%   argument needs to be grabbed without removing any braces at all. If
+%   this is not done, then cases like |[{[}]| fail. So after testing for
+%   an optional argument, it is collected piece-wise. Inserting a quark
+%   prevents loss of braces, and there is then a test to see if there are
+%   nested delimiters to handle.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_D_aux:NNnNN #1#2#3#4#5
+  {
+    \@@_grab_D_aux:NNnN #1#2 {#3} #4
+    #5 #1
+      { \@@_grab_D_call:Nw #1 }
+      { \@@_add_arg:o \c_novalue_tl }
+  }
+%    \end{macrocode}
+%   Inside the \enquote{standard} grabber, there is a test to see if the
+%   grabbed argument is entirely enclosed by braces. There are a couple of
+%   extra factors to allow for: the argument might be entirely empty, and
+%   spaces at the start and end of the input must be retained around a brace
+%   group. Also notice that a \emph{blank} argument might still contain
+%   spaces.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_D_aux:NNnN #1#2#3#4
+  {
+    \tl_set:Nn \l_@@_signature_tl {#3}
+    \exp_after:wN #4 \l_@@_fn_tl ##1 #2
+      {
+        \tl_if_in:nnTF {##1} {#1}
+          { \@@_grab_D_nested:NNnN #1 #2 {##1} #4 }
+          {
+            \tl_if_blank:oTF { \use_none:n ##1 }
+              { \@@_add_arg:o { \use_none:n ##1 } }
+              {
+                \str_if_eq:eeTF
+                  { \exp_not:o { \use_none:n ##1 } }
+                  { { \exp_not:o { \use_ii:nnn ##1 \q_nil } } }
+                  { \@@_add_arg:o { \use_ii:nn ##1 } }
+                  { \@@_add_arg:o { \use_none:n ##1 } }
+              }
+          }
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \begin{macro}{\@@_grab_D_nested:NNnN}
+% \begin{macro}{\@@_grab_D_nested:w}
+% \begin{macro}{\l_@@_nesting_a_tl}
+% \begin{macro}{\l_@@_nesting_b_tl}
+% \begin{macro}{\q_@@}
+%   Catching nested optional arguments means more work. The aim here is
+%   to collect up each pair of optional tokens without \TeX{} helping out,
+%   and without counting anything. The code above will already have
+%   removed the leading opening token and a closing token, but the
+%   wrong one. The aim is then to work through the material grabbed
+%   so far and divide it up on each opening token, grabbing a closing
+%   token to match (thus working in pairs). Once there are no opening
+%   tokens, then there is a second check to see if there are any
+%   opening tokens in the second part of the argument (for things
+%   like |[][]|). Once everything has been found, the entire collected
+%   material is added to the output as a single argument. The only tricky part
+%   here is ensuring that any grabbing function that might run away is named
+%   after the function currently being parsed and not after \pkg{xparse}. That
+%   leads to some rather complex nesting! There is also a need to prevent the
+%   loss of any braces, hence the insertion and removal of quarks along the
+%   way.
+%    \begin{macrocode}
+\tl_new:N \l_@@_nesting_a_tl
+\tl_new:N \l_@@_nesting_b_tl
+\quark_new:N \q_@@
+\cs_new_protected:Npn \@@_grab_D_nested:NNnN #1#2#3#4
+  {
+    \tl_clear:N \l_@@_nesting_a_tl
+    \tl_clear:N \l_@@_nesting_b_tl
+    \exp_after:wN #4 \l_@@_fn_tl ##1 #1 ##2 \q_@@ ##3 #2
+      {
+        \tl_put_right:No \l_@@_nesting_a_tl { \use_none:n ##1 #1 }
+        \tl_put_right:No \l_@@_nesting_b_tl { \use_i:nn #2 ##3 }
+        \tl_if_in:nnTF {##2} {#1}
+          {
+            \l_@@_fn_tl
+              \q_nil ##2 \q_@@ \ERROR
+          }
+          {
+            \tl_put_right:Nx \l_@@_nesting_a_tl
+              { \@@_grab_D_nested:w \q_nil ##2 \q_stop }
+            \tl_if_in:NnTF \l_@@_nesting_b_tl {#1}
+              {
+                \tl_set_eq:NN \l_@@_tmpa_tl \l_@@_nesting_b_tl
+                \tl_clear:N \l_@@_nesting_b_tl
+                \exp_after:wN \l_@@_fn_tl \exp_after:wN
+                  \q_nil \l_@@_tmpa_tl \q_nil \q_@@ \ERROR
+              }
+              {
+                \tl_put_right:No \l_@@_nesting_a_tl
+                  \l_@@_nesting_b_tl
+                \@@_add_arg:V \l_@@_nesting_a_tl
+              }
+          }
+      }
+    \l_@@_fn_tl #3 \q_nil \q_@@ \ERROR
+  }
+\cs_new:Npn \@@_grab_D_nested:w #1 \q_nil \q_stop
+  { \exp_not:o { \use_none:n #1 } }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \begin{macro}{\@@_grab_D_call:Nw}
+%   For \texttt{D} and \texttt{R}-type arguments, to avoid losing any
+%   braces, a token needs to be inserted before the argument to be grabbed.
+%   If the argument runs away because the closing token is missing then this
+%   inserted token shows up in the terminal. Ideally, |#1| would therefore be
+%   used directly, but that is no good as it will mess up the rest of the
+%   grabber. Instead, a copy of |#1| with an altered category code is used,
+%   as this will look right in the terminal but will not mess up the grabber.
+%   The only issue then is that the category code of |#1| is unknown. So there
+%   is a quick test to ensure that the inserted token can never be matched by
+%   the grabber. (This assumes that the open and close delimiters are not the
+%   same character with different category codes, but that really should not
+%   happen in any sensible document-level syntax.)
+%   An exception is when |#1| is a control sequence token, in which case the
+%   character-token treatment is no good because if hit with \cs{token_to_str:N}
+%   it would add sputios tokens to the argument. In this case a different
+%   branch is taken. The token inserted is then the same \meta{csname} as |#1|,
+%   but with a space appended, so that the grabber don't see it as another
+%   of the same delimiter.
+%    \begin{macrocode}
+\cs_new_protected_nopar:Npn \@@_grab_D_call:Nw #1
+  {
+    \token_if_eq_catcode:NNTF + #1
+      {
+        \exp_after:wN \exp_after:wN \exp_after:wN
+          \l_@@_fn_tl \char_generate:nn { `#1 } { 11 }
+      }
+      {
+        \@@_token_if_cs:NTF #1
+          {
+            \exp_after:wN \l_@@_fn_tl
+            \cs:w \cs_to_str:N #1 ~ \cs_end:
+          }
+          {
+            \exp_after:wN \l_@@_fn_tl
+            \token_to_str:N #1
+          }
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+%   {
+%     \@@_grab_E:w, \@@_grab_E_long:w,
+%     \@@_grab_E_obey_spaces:w, \@@_grab_E_long_obey_spaces:w
+%   }
+% \begin{macro}{\@@_grab_E:nnNN}
+% \begin{macro}{\@@_grab_E_loop:NnN}
+% \begin{macro}{\@@_grab_E_finalise:}
+%   Everything here needs to point to a loop.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_E:w #1#2 \@@_run_code:
+  {
+    \@@_grab_E:nnNN {#1} {#2}
+      \cs_set_protected_nopar:Npn
+      \@@_peek_nonspace_remove:NTF
+  }
+\cs_new_protected:Npn \@@_grab_E_long:w #1#2 \@@_run_code:
+  {
+    \@@_grab_E:nnNN {#1} {#2}
+      \cs_set_protected:Npn
+      \@@_peek_nonspace_remove:NTF
+  }
+\cs_new_protected:Npn \@@_grab_E_obey_spaces:w #1#2 \@@_run_code:
+  {
+    \@@_grab_E:nnNN {#1} {#2}
+      \cs_set_protected_nopar:Npn
+      \@@_peek_meaning_remove:NTF
+  }
+\cs_new_protected:Npn \@@_grab_E_long_obey_spaces:w #1#2 \@@_run_code:
+  {
+    \@@_grab_E:nnNN {#1} {#2}
+      \cs_set_protected:Npn
+      \@@_peek_meaning_remove:NTF
+  }
+%    \end{macrocode}
+%   A loop is needed here to allow a random ordering of keys. These are
+%   searched for one at a time, with any not found needing to be tracked:
+%   they can appear later. The grabbed values are held in a property list
+%   which is then turned into an ordered list to be passed back to the user.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_E:nnNN #1#2#3#4
+  {
+    \exp_after:wN #3 \l_@@_fn_tl ##1##2##3
+      {
+        \prop_put:Nnn \l_@@_tmp_prop {##1} {##3}
+        \@@_grab_E_loop:NnN #4 { } ##2 \q_recursion_stop
+      }
+    \prop_clear:N \l_@@_tmp_prop
+    \tl_set:Nn \l_@@_signature_tl {#2}
+    \cs_set_protected:Npn \@@_grab_E_finalise:
+      {
+        \tl_map_inline:nn {#1}
+          {
+            \prop_get:NnNF \l_@@_tmp_prop {####1} \l_@@_tmpb_tl
+              { \tl_set_eq:NN \l_@@_tmpb_tl \c_novalue_tl }
+            \tl_put_right:Nx \l_@@_args_tl
+              { { \exp_not:V \l_@@_tmpb_tl } }
+          }
+        \l_@@_signature_tl \@@_run_code:
+      }
+    \@@_grab_E_loop:NnN #4 { } #1 \q_recursion_tail \q_recursion_stop
+  }
+\cs_new_protected:Npn \@@_grab_E_loop:NnN #1#2#3#4 \q_recursion_stop
+  {
+    \cs_if_eq:NNTF #3 \q_recursion_tail
+      { \@@_grab_E_finalise: }
+      {
+        #1 #3
+          { \l_@@_fn_tl #3 {#2#4} }
+          { \@@_grab_E_loop:NnN #1 {#2#3} #4 \q_recursion_stop }
+      }
+  }
+\cs_new_protected:Npn \@@_grab_E_finalise: { }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+%
+% \begin{macro}{\@@_grab_m:w}
+% \begin{macro}{\@@_grab_m_long:w}
+%   Collecting a single mandatory argument is quite easy.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_m:w #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \exp_after:wN \cs_set_protected_nopar:Npn \l_@@_fn_tl ##1
+      { \@@_add_arg:n {##1} }
+    \l_@@_fn_tl
+  }
+\cs_new_protected:Npn \@@_grab_m_long:w #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \exp_after:wN \cs_set_protected:Npn \l_@@_fn_tl ##1
+      { \@@_add_arg:n {##1} }
+    \l_@@_fn_tl
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_m_1:w}
+% \begin{macro}{\@@_grab_m_2:w}
+% \begin{macro}{\@@_grab_m_3:w}
+% \begin{macro}{\@@_grab_m_4:w}
+% \begin{macro}{\@@_grab_m_5:w}
+% \begin{macro}{\@@_grab_m_6:w}
+% \begin{macro}{\@@_grab_m_7:w}
+% \begin{macro}{\@@_grab_m_8:w}
+% \begin{macro}{\@@_grab_m_9:w}
+% \begin{macro}{\@@_grab_m_aux:Nnnnnnnnn}
+%   Grabbing 1--8 mandatory arguments is done by giving 8--1 known
+%   arguments to a 9-argument function that stores them in
+%   \cs{l_@@_args_tl}.  For simplicity, grabbing 9 mandatory arguments
+%   is done by grabbing 5 then 4 arguments.
+%    \begin{macrocode}
+\cs_new_protected_nopar:Npn \@@_grab_m_aux:Nnnnnnnnn #1#2#3#4#5#6#7#8#9
+  {
+    \tl_put_right:No \l_@@_args_tl
+      { #1 {#2} {#3} {#4} {#5} {#6} {#7} {#8} {#9} }
+    \l_@@_signature_tl \@@_run_code:
+  }
+\cs_new_protected:cpn { @@_grab_m_1:w } #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+    \l_@@_fn_tl \use_none:nnnnnnn { } { } { } { } { } { } { }
+  }
+\cs_new_protected:cpn { @@_grab_m_2:w } #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+    \l_@@_fn_tl \use_none:nnnnnn { } { } { } { } { } { }
+  }
+\cs_new_protected:cpn { @@_grab_m_3:w } #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+    \l_@@_fn_tl \use_none:nnnnn { } { } { } { } { }
+  }
+\cs_new_protected:cpn { @@_grab_m_4:w } #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+    \l_@@_fn_tl \use_none:nnnn { } { } { } { }
+  }
+\cs_new_protected:cpn { @@_grab_m_5:w } #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+    \l_@@_fn_tl \use_none:nnn { } { } { }
+  }
+\cs_new_protected:cpn { @@_grab_m_6:w } #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+    \l_@@_fn_tl \use_none:nn { } { }
+  }
+\cs_new_protected:cpn { @@_grab_m_7:w } #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+    \l_@@_fn_tl \use_none:n { }
+  }
+\cs_new_protected:cpn { @@_grab_m_8:w } #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \exp_after:wN \cs_set_eq:NN \l_@@_fn_tl \@@_grab_m_aux:Nnnnnnnnn
+    \l_@@_fn_tl \prg_do_nothing:
+  }
+\cs_new_protected:cpx { @@_grab_m_9:w }
+  {
+    \exp_not:c { @@_grab_m_5:w }
+    \exp_not:c { @@_grab_m_4:w }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_R:w, \@@_grab_R_long:w}
+% \begin{macro}{\@@_grab_R_aux:NNnN}
+%  The grabber for \texttt{R}-type arguments is basically the same as
+%  that for \texttt{D}-type ones, but always skips spaces (as it is mandatory)
+%  and has a hard-coded error message.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_R:w #1#2#3 \@@_run_code:
+  { \@@_grab_R_aux:NNnN #1 #2 {#3} \cs_set_protected_nopar:Npn }
+\cs_new_protected:Npn \@@_grab_R_long:w #1#2#3 \@@_run_code:
+  { \@@_grab_R_aux:NNnN #1 #2 {#3} \cs_set_protected:Npn }
+\cs_new_protected:Npn \@@_grab_R_aux:NNnN #1#2#3#4
+  {
+    \@@_grab_D_aux:NNnN #1 #2 {#3} #4
+    \@@_peek_nonspace_remove:NTF #1
+      { \@@_grab_D_call:Nw #1 }
+      {
+        \__kernel_msg_error:nnxx { ltcmd } { missing-required }
+          { \@@_environment_or_command: }
+          { \token_to_str:N #1 }
+        \@@_add_arg:o \c_novalue_tl
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_t:w}
+% \begin{macro}{\@@_grab_t_obey_spaces:w}
+% \begin{macro}{\@@_grab_t_aux:NNw}
+%   Dealing with a token is quite easy. Check the match, remove the
+%   token if needed and add a flag to the output.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_t:w
+  { \@@_grab_t_aux:NNw \@@_peek_nonspace_remove:NTF }
+\cs_new_protected:Npn \@@_grab_t_obey_spaces:w
+  { \@@_grab_t_aux:NNw \@@_peek_meaning_remove:NTF }
+\cs_new_protected:Npn \@@_grab_t_aux:NNw #1#2#3 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#3}
+    \exp_after:wN \cs_set_protected:Npn \l_@@_fn_tl
+      {
+        #1 #2
+          { \@@_add_arg:n { \BooleanTrue } }
+          { \@@_add_arg:n { \BooleanFalse } }
+      }
+    \l_@@_fn_tl
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{variable}{\l_@@_v_arg_tl}
+%    \begin{macrocode}
+\tl_new:N \l_@@_v_arg_tl
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_grab_v:w}
+% \begin{macro}{\@@_grab_v_long:w}
+% \begin{macro}{\@@_grab_v_aux:w}
+% \begin{macro}{\@@_grab_v_group_end:}
+%   The opening delimiter is the first non-space token, and is never
+%   read verbatim.  This is required by consistency with the case where
+%   the preceding argument was optional and absent: then \TeX{} has
+%   already read and tokenized that token when looking for the optional
+%   argument.  The first thing is thus to check is that this delimiter
+%   is a character, and to distinguish the case of a left brace (in that
+%   case, \cs{group_align_safe_end:} is needed to compensate for the
+%   begin-group character that was just seen).  Then set verbatim
+%   catcodes with \cs{@@_grab_v_aux_catcodes:}.
+%
+%   The group keep catcode changes local, and
+%   \cs{group_align_safe_begin/end:} allow to use a character
+%   with category code~$4$ (normally |&|) as the delimiter (all commands
+%   do \cs{group_align_safe_begin/end:}, so there's no need to do that
+%   again here).
+%   It is ended by \cs{@@_grab_v_group_end:}, which smuggles
+%   the collected argument out of the group.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_v:w
+  {
+    \bool_set_false:N \l_@@_long_bool
+    \@@_grab_v_aux:w
+  }
+\cs_new_protected:Npn \@@_grab_v_long:w
+  {
+    \bool_set_true:N \l_@@_long_bool
+    \@@_grab_v_aux:w
+  }
+\cs_new_protected:Npn \@@_grab_v_aux:w #1 \@@_run_code:
+  {
+    \tl_set:Nn \l_@@_signature_tl {#1}
+    \group_begin:
+      \tex_escapechar:D = 92 \scan_stop:
+      \tl_clear:N \l_@@_v_arg_tl
+      \peek_remove_spaces:n
+        {
+          \peek_meaning_remove:NTF \c_group_begin_token
+            {
+              \group_align_safe_end:
+              \@@_grab_v_bgroup:
+            }
+            {
+              \peek_N_type:TF
+                { \@@_grab_v_aux_test:N }
+                { \@@_grab_v_aux_abort:n { } }
+            }
+        }
+  }
+\cs_new_protected:Npn \@@_grab_v_group_end:
+  {
+        \exp_args:NNNo
+      \group_end:
+    \tl_set:Nn \l_@@_v_arg_tl { \l_@@_v_arg_tl }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_v_aux_test:N}
+% \begin{macro}
+%   {
+%     \@@_grab_v_aux_loop:N,
+%     \@@_grab_v_aux_loop:NN,
+%     \@@_grab_v_aux_loop_end:
+%   }
+%   Check that the opening delimiter is a character, setup category codes,
+%   then start reading tokens one by one, keeping the delimiter as an argument.
+%   If the verbatim was not nested, we will be grabbing one character
+%   at each step. Unfortunately, it can happen that what follows the
+%   verbatim argument is already tokenized. Thus, we check at each step
+%   that the next token is indeed a \enquote{nice}
+%   character, \emph{i.e.}, is not a character with
+%   category code $1$ (begin-group), $2$ (end-group)
+%   or $6$ (macro parameter), nor the space character,
+%   with category code~$10$ and character code~$32$,
+%   nor a control sequence.
+%   The partially built argument is stored in \cs{l_@@_v_arg_tl}.
+%   If we ever meet a token which we cannot grab (non-N-type),
+%   or which is not a character according to
+%   \cs{@@_grab_v_token_if_char:NTF}, then we bail out with
+%   \cs{@@_grab_v_aux_abort:n}. Otherwise, we stop at the first
+%   character matching the delimiter.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_v_aux_test:N #1
+  {
+    \@@_grab_v_token_if_char:NTF #1
+      {
+        \@@_grab_v_aux_put:N #1
+        \@@_grab_v_aux_catcodes:
+        \@@_grab_v_aux_loop:N #1
+      }
+      { \@@_grab_v_aux_abort:n {#1} #1 }
+  }
+\cs_new_protected:Npn \@@_grab_v_aux_loop:N #1
+  {
+    \peek_N_type:TF
+      { \@@_grab_v_aux_loop:NN #1 }
+      { \@@_grab_v_aux_abort:n { } }
+  }
+\cs_new_protected:Npn \@@_grab_v_aux_loop:NN #1#2
+  {
+    \@@_grab_v_token_if_char:NTF #2
+      {
+        \token_if_eq_charcode:NNTF #1 #2
+          { \@@_grab_v_aux_loop_end: }
+          {
+            \@@_grab_v_aux_put:N #2
+            \@@_grab_v_aux_loop:N #1
+          }
+      }
+      { \@@_grab_v_aux_abort:n {#2} #2 }
+  }
+\cs_new_protected:Npn \@@_grab_v_aux_loop_end:
+  {
+    \@@_grab_v_group_end:
+    \@@_add_arg:x { \tl_tail:N \l_@@_v_arg_tl }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{variable}{\l_@@_v_nesting_int}
+%    \begin{macrocode}
+\int_new:N \l_@@_v_nesting_int
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_grab_v_bgroup:}
+% \begin{macro}{\@@_grab_v_bgroup_loop:}
+% \begin{macro}{\@@_grab_v_bgroup_loop:N}
+%   If the opening delimiter is a left brace, we keep track of
+%   how many left and right braces were encountered so far in
+%   \cs{l_@@_v_nesting_int} (the methods used for optional
+%   arguments cannot apply here), and stop as soon as it reaches~$0$.
+%
+%   Some care was needed when removing the opening delimiter, which
+%   has already been assigned category code~$1$: using
+%   \cs{peek_meaning_remove:NTF} in the \cs{@@_grab_v_aux:w}
+%   function would break within alignments. Instead, we first
+%   convert that token to a string, and remove the result as a
+%   normal undelimited argument.
+%    \begin{macrocode}
+\cs_new_protected:Npx \@@_grab_v_bgroup:
+  {
+    \exp_not:N \@@_grab_v_aux_catcodes:
+    \exp_not:n { \int_set:Nn \l_@@_v_nesting_int { 1 } }
+    \exp_not:N \@@_grab_v_aux_put:N \iow_char:N \{
+    \exp_not:N \@@_grab_v_bgroup_loop:
+  }
+\cs_new_protected:Npn \@@_grab_v_bgroup_loop:
+  {
+    \peek_N_type:TF
+      { \@@_grab_v_bgroup_loop:N }
+      { \@@_grab_v_aux_abort:n { } }
+  }
+\cs_new_protected:Npn \@@_grab_v_bgroup_loop:N #1
+  {
+    \@@_grab_v_token_if_char:NTF #1
+      {
+        \token_if_eq_charcode:NNTF \c_group_end_token #1
+          {
+            \int_decr:N \l_@@_v_nesting_int
+            \int_compare:nNnTF \l_@@_v_nesting_int > 0
+              {
+                \@@_grab_v_aux_put:N #1
+                \@@_grab_v_bgroup_loop:
+              }
+              { \@@_grab_v_aux_loop_end: }
+          }
+          {
+            \token_if_eq_charcode:NNT \c_group_begin_token #1
+              { \int_incr:N \l_@@_v_nesting_int }
+            \@@_grab_v_aux_put:N #1
+            \@@_grab_v_bgroup_loop:
+          }
+      }
+      { \@@_grab_v_aux_abort:n {#1} #1 }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_v_aux_catcodes:}
+% \begin{macro}{\@@_grab_v_aux_abort:n}
+%   The approach for short verbatim arguments is to make the end-line
+%   character a macro parameter character: this is forbidden by the
+%   rest of the code. Then the error branch can check what caused the
+%   bail out and give the appropriate error message.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_v_aux_catcodes:
+  {
+    \cs_set_eq:NN \do \char_set_catcode_other:N
+    \dospecials
+    \tex_endlinechar:D = `\^^M \scan_stop:
+    \bool_if:NTF \l_@@_long_bool
+      { \char_set_catcode_other:n { \tex_endlinechar:D } }
+      { \char_set_catcode_parameter:n { \tex_endlinechar:D } }
+  }
+\cs_new_protected:Npn \@@_grab_v_aux_abort:n #1
+  {
+    \@@_grab_v_group_end:
+    \exp_after:wN \exp_after:wN \exp_after:wN
+      \peek_meaning_remove:NTF \char_generate:nn { \tex_endlinechar:D } { 6 }
+      {
+        \__kernel_msg_error:nnxxx { ltcmd } { verbatim-newline }
+          { \@@_environment_or_command: }
+          { \tl_to_str:N \l_@@_v_arg_tl }
+          { \tl_to_str:n {#1} }
+        \@@_add_arg:o \c_novalue_tl
+      }
+      {
+        \__kernel_msg_error:nnxxx { ltcmd } { verbatim-tokenized }
+          { \@@_environment_or_command: }
+          { \tl_to_str:N \l_@@_v_arg_tl }
+          { \tl_to_str:n {#1} }
+        \@@_add_arg:o \c_novalue_tl
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_v_aux_put:N}
+%   Storing one token in the collected argument. Most tokens are
+%   converted to category code $12$, with the exception of active
+%   characters, and spaces (not sure what should be done for those).
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_v_aux_put:N #1
+  {
+    \tl_put_right:Nx \l_@@_v_arg_tl
+      {
+        \token_if_active:NTF #1
+          { \exp_not:N #1 } { \token_to_str:N #1 }
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_grab_v_token_if_char:NTF}
+%   This function assumes that the escape character is printable.
+%   Then the string representation of control sequences is at least
+%   two characters, and \cs{str_tail:n} only removes the escape
+%   character. Macro parameter characters are doubled by
+%   \cs{tl_to_str:n}, and will also yield a non-empty result,
+%   hence are not considered as characters.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_grab_v_token_if_char:NTF #1
+  { \str_if_eq:eeTF { } { \str_tail:n {#1} } }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_add_arg:n, \@@_add_arg:V, \@@_add_arg:o, \@@_add_arg:x}
+%   When an argument is found it is stored, then further arguments are
+%   grabbed by calling \cs{l_@@_signature_tl}.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_add_arg:n #1
+  {
+    \tl_put_right:Nn \l_@@_args_tl { {#1} }
+    \l_@@_signature_tl \@@_run_code:
+  }
+\cs_generate_variant:Nn \@@_add_arg:n { V , o , x }
+%    \end{macrocode}
+% \end{macro}
+%
+% \subsection{Grabbing arguments expandably}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_D:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_D:NNNwNNn}
+% \begin{macro}[EXP]{\@@_expandable_grab_D:NNNwNNnnn}
+% \begin{macro}[EXP]{\@@_expandable_grab_D:Nw}
+% \begin{macro}[EXP]{\@@_expandable_grab_D:nnNNNwNN}
+%   The first step is to grab the first token or group. The generic grabbers
+%   \cs{\meta{function}}\verb*| | and \cs{\meta{function}}\verb*| | are just after \cs{q_@@}, we go and find
+%   them (and use the long one).
+%    \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_D:w #1 \q_@@ #2#3
+  { #2 { \@@_expandable_grab_D:NNNwNNn #1 \q_@@ #2 #3 } }
+%    \end{macrocode}
+%   We then wish to test whether |#7|, which we just grabbed, is exactly |#2|.
+%   A preliminary test is whether their string representations coincide, then
+%   expand the only grabber function we have, |#1|, once: the two strings below
+%   are equal if and only if |#7| matches |#2| exactly.\footnote{It is obvious
+%   that if \texttt{\#7} matches \texttt{\#2} then the strings are equal. We
+%   must check the converse. The right-hand-side of \cs{str_if_eq:onTF} does
+%   not end with \texttt{\#3}, implying that the grabber function took
+%   everything as its arguments. The first brace group can only be empty if
+%   \texttt{\#7} starts with \texttt{\#2}, otherwise the brace group preceding
+%   \texttt{\#7} would not vanish. The third brace group is empty, thus the
+%   \cs{q_@@} that was used by our grabber \texttt{\#1} must be the one
+%   that we inserted (not some token in \texttt{\#7}), hence the second brace
+%   group contains the end of \texttt{\#7} followed by \texttt{\#2}. Since this
+%   is \texttt{\#2} on the right-hand-side, and no brace can be lost there,
+%   \texttt{\#7} must contain nothing else than its leading \texttt{\#2}.}
+%   The preliminary test is needed as |#7| could validly contain
+%   \tn{par} (because a later mandatory argument could be long) and our
+%   grabber may be short.  If
+%   |#7| does not match |#2|, then the optional argument is missing, we use the
+%   default |-NoValue-|, and put back the argument |#7| in the input stream.
+%
+%   If it does match, then interesting things need to be done. We will grab the
+%   argument piece by piece, with the following pattern:
+%   \begin{quote}
+%     \meta{grabber} \Arg{tokens} \\
+%     ~~\cs{q_nil} \Arg{piece 1} \meta{piece 2} \cs{ERROR} \cs{q_@@}\\
+%     ~~\cs{q_nil} \meta{input stream}
+%   \end{quote}
+%   The \meta{grabber} will find an opening delimiter in \meta{piece 2}, take
+%   the \cs{q_@@} as a second delimiter, and find more material delimited
+%   by the closing delimiter in the \meta{input stream}. We then move the part
+%   before the opening delimiter from \meta{piece 2} to \meta{piece 1}, and the
+%   material taken from the \meta{input stream} to the \meta{piece 2}. Thus,
+%   the argument moves gradually from the \meta{input stream} to the
+%   \meta{piece 2}, then to the \meta{piece 1} when we have made sure to find
+%   all opening and closing delimiters. This two-step process ensures that
+%   nesting works: the number of opening delimiters minus closing delimiters in
+%   \meta{piece 1} is always equal to the number of closing delimiters in
+%   \meta{piece 2}. We stop grabbing arguments once the \meta{piece 2} contains
+%   no opening delimiter any more, hence the balance is reached, and the final
+%   argument is \meta{piece 1} \meta{piece 2}.
+%   The indirection via \cs{@@_tmp:w} allows to insert |-NoValue-| expanded.
+%    \begin{macrocode}
+\cs_set_protected:Npn \@@_tmp:w #1
+  {
+    \cs_new:Npn \@@_expandable_grab_D:NNNwNNn ##1##2##3##4 \q_@@ ##5##6##7
+      {
+        \str_if_eq:nnTF {##2} {##7}
+          {
+            \str_if_eq:onTF
+              { ##1 { } { } ##7 ##2 \q_@@ ##3 }
+              { { } {##2} { } }
+          }
+          { \use_ii:nn }
+          {
+            ##1
+              { \@@_expandable_grab_D:NNNwNNnnn ##1##2##3##4 \q_@@ ##5##6 }
+              \q_nil { } ##2 \ERROR \q_@@ \ERROR
+          }
+          { ##4 {#1} \q_@@ ##5 ##6 {##7} }
+      }
+  }
+\exp_args:No \@@_tmp:w { \c_novalue_tl }
+%    \end{macrocode}
+%   At this stage, |#7| is \cs{q_nil} \Arg{piece 1} \meta{more for piece 1},
+%   and we want to concatenate all that, removing \cs{q_nil}, and keeping the
+%   opening delimiter |#2|. Simply use \cs{use_ii:nn}. Also, |#8| is
+%   \meta{remainder of piece 2} \cs{ERROR}, and |#9| is \cs{ERROR} \meta{more
+%   for piece 2}. We concatenate those, replacing the two \cs{ERROR} by the
+%   closing delimiter |#3|.
+%    \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_D:NNNwNNnnn #1#2#3#4 \q_@@ #5#6#7#8#9
+  {
+    \exp_args:Nof \@@_expandable_grab_D:nnNNNwNN
+      { \use_ii:nn #7 #2 }
+      { \@@_expandable_grab_D:Nw #3 \exp_stop_f: #8 #9 }
+    #1#2#3 #4 \q_@@ #5 #6
+  }
+\cs_new:Npn \@@_expandable_grab_D:Nw #1#2 \ERROR \ERROR { #2 #1 }
+%    \end{macrocode}
+%   Armed with our two new \meta{pieces}, we are ready to loop. However, we
+%   must first see if \meta{piece 2} (here |#2|) contains any opening
+%   delimiter |#4|. Again, we expand |#3|, this time removing its whole output
+%   with \cs{use_none:nnn}. The test is similar to \cs{tl_if_in:nnTF}. The
+%   token list is empty if and only if |#2| does not contain the opening
+%   delimiter. In that case, we are done, and put the argument (from which we
+%   remove a spurious pair of delimiters coming from how we started the loop).
+%   Otherwise, we go back to looping with
+%   \cs{@@_expandable_grab_D:NNNwNNnnn}. The code to deal with brace stripping
+%   is much the same as for the non-expandable case.
+%    \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_D:nnNNNwNN #1#2#3#4#5#6 \q_@@ #7#8
+  {
+    \exp_args:No \tl_if_empty:oTF
+      { #3 { \use_none:nnn } #2 \q_@@ #5 #4 \q_@@ #5 }
+      {
+        \tl_if_blank:oTF { \use_none:nn #1#2 }
+          { \@@_put_arg_expandable:ow { \use_none:nn #1#2 } }
+          {
+            \str_if_eq:eeTF
+              { \exp_not:o { \use_none:nn #1#2 } }
+              { { \exp_not:o { \use_iii:nnnn #1#2 \q_nil } } }
+              { \@@_put_arg_expandable:ow { \use_iii:nnn #1#2 } }
+              { \@@_put_arg_expandable:ow { \use_none:nn #1#2 } }
+          }
+            #6 \q_@@ #7 #8
+      }
+      {
+        #3
+          { \@@_expandable_grab_D:NNNwNNnnn #3#4#5#6 \q_@@ #7 #8 }
+          \q_nil {#1} #2 \ERROR \q_@@ \ERROR
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_D_alt:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_D_alt:NNwNNn}
+% \begin{macro}[EXP]{\@@_expandable_grab_D_alt:Nwn}
+%   When the delimiters are identical, nesting is not possible and a simplified
+%   approach is used. The test concept here is the same as for the case where
+%   the delimiters are different but there cannot be any nesting.
+%    \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_D_alt:w #1 \q_@@ #2#3
+  { #2 { \@@_expandable_grab_D_alt:NNwNNn #1 \q_@@ #2 #3 } }
+\cs_set_protected:Npn \@@_tmp:w #1
+  {
+    \cs_new:Npn \@@_expandable_grab_D_alt:NNwNNn ##1##2##3 \q_@@ ##4##5##6
+      {
+        \str_if_eq:nnTF {##6} {##2}
+          {
+            \str_if_eq:onTF
+              { ##1 { } ##6 ##2 ##2 }
+              { { } ##2 }
+          }
+          { \use_ii:nn }
+          {
+            ##1
+              { \@@_expandable_grab_D_alt:NNwn ##4 ##5 ##3 \q_@@ }
+              ##6 \ERROR
+          }
+          { ##3 {#1} \q_@@ ##4 ##5 {##6} }
+      }
+  }
+\exp_args:No \@@_tmp:w { \c_novalue_tl }
+\cs_new:Npn \@@_expandable_grab_D_alt:NNwn #1#2#3 \q_@@ #4
+  {
+    \tl_if_blank:oTF { \use_none:n #4 }
+      { \@@_put_arg_expandable:ow { \use_none:n #4 } }
+      {
+        \str_if_eq:eeTF
+          { \exp_not:o { \use_none:n #4 } }
+          { { \exp_not:o { \use_ii:nnn #4 \q_nil } } }
+          { \@@_put_arg_expandable:ow { \use_ii:nn #4 } }
+          { \@@_put_arg_expandable:ow { \use_none:n #4 } }
+      }
+        #3 \q_@@ #1 #2
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_E:w, \@@_expandable_grab_E_long:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_aux:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_test:nnw}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_loop:nnnNNw}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_find:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_find:nnw}
+% \begin{macro}[EXP]{\@@_expandable_grab_E_end:nnw}
+%   We keep track of long/short by placing the appropriate grabber as
+%   the third token after \cs{q_@@}; it is eventually removed by the
+%   \texttt{end:nnw} auxiliary.  The \texttt{aux:w} auxiliary will be
+%   called repeatedly with two arguments: the set
+%   of pairs \meta{parser} \meta{token}, and the set of arguments found
+%   so far (initially all |{-NoValue-}|).  At each step, grab what
+%   follows in the input stream then call the \texttt{loop:nnnNNw}
+%   auxiliary to compare it with each possible embellishment in turn.
+%   This auxiliary's |#1| is what was found in the input, |#2| collects
+%   \meta{parser} \meta{token} pairs that did not match, |#3| collects
+%   the corresponding arguments found previously, |#4| and |#5| is the
+%   current pair, |#6| is the remaining pairs, |#7| is empty or two
+%   \cs{q_nil}, and |#8| is the current argument.  If none of the pairs
+%   matched (determined by \cs{quark_if_nil:NTF}) then call the
+%   \texttt{end} auxiliary to stop looking for embellishments,
+%   remembering to put what was grabbed in the input back where it
+%   belongs, and storing the arguments found just before \cs{q_@@}.  If
+%   the current argument |#8| is not |-NoValue-| or if the input |#1|
+%   does not match |#5| (see \texttt{t}-type arguments below for a
+%   similar \cs{str_if_eq:onTF} test) then carry on the loop.
+%   Otherwise, we found a new embellishment: grab the corresponding
+%   argument in the input using the \texttt{find:w} auxiliary.  To avoid
+%   losing braces around that auxiliary's argument we include a
+%   space, which will be eliminated in the next loop through
+%   embellishments.
+%    \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_E:w #1 \q_@@ #2#3
+  { \@@_expandable_grab_E_aux:w #1 \q_@@ #2 #3 #3 }
+\cs_new:Npn \@@_expandable_grab_E_long:w #1 \q_@@ #2#3
+  { \@@_expandable_grab_E_aux:w #1 \q_@@ #2 #3 #2 }
+\cs_new:Npn \@@_expandable_grab_E_aux:w #1 \q_@@ #2#3#4
+  { #2 { \@@_expandable_grab_E_test:nnw #1 \q_@@ #2 #3 #4 } }
+\cs_new:Npn \@@_expandable_grab_E_test:nnw #1#2#3 \q_@@ #4#5#6#7
+  {
+    \@@_expandable_grab_E_loop:nnnNNw {#7} { } { }
+      #1 \q_nil \q_nil \q_nil \q_mark #2 \q_nil
+    #3 \q_@@ #4 #5 #6
+  }
+\cs_new:Npn \@@_expandable_grab_E_loop:nnnNNw
+    #1#2#3#4#5#6 \q_nil #7 \q_mark #8
+  {
+    \quark_if_nil:NTF #4
+      { \@@_expandable_grab_E_end:nnw {#1} {#3} }
+      {
+        \tl_if_novalue:nTF {#8}
+          { \str_if_eq:onTF { #4 { } #1 #5 } {#5} }
+          { \use_ii:nn }
+            { \@@_expandable_grab_E_find:w { #2 #4 #5 #6 } {#3} ~ }
+            {
+              \@@_expandable_grab_E_loop:nnnNNw
+                {#1} { #2 #4 #5 } { #3 {#8} }
+                #6 \q_nil #7 \q_mark
+            }
+      }
+  }
+\cs_new:Npn \@@_expandable_grab_E_find:w #1 \q_@@ #2#3#4
+  { #4 { \@@_expandable_grab_E_find:nnw #1 \q_@@ #2 #3 #4 } }
+\cs_new:Npn \@@_expandable_grab_E_find:nnw #1#2#3 \q_nil #4 \q_@@ #5#6#7#8
+  { \@@_expandable_grab_E_aux:w {#1} { #2 {#8} #3 } #4 \q_@@ #5 #6 #7 }
+\cs_new:Npn \@@_expandable_grab_E_end:nnw #1#2#3 \q_@@ #4#5#6
+  { #3 #2 \q_@@ #4 #5 {#1} }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_m:w, \@@_expandable_grab_m_long:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_m_aux:wNn}
+%   The mandatory case is easy: find the auxiliary after the \cs{q_@@},
+%   and use it directly to grab the argument, then correctly position
+%   the argument before \cs{q_@@}.
+%    \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_m:w #1 \q_@@ #2#3
+  { #3 { \@@_expandable_grab_m_aux:wNn #1 \q_@@ #2 #3 } }
+\cs_new:Npn \@@_expandable_grab_m_long:w #1 \q_@@ #2#3
+  { #2 { \@@_expandable_grab_m_aux:wNn #1 \q_@@ #2 #3 } }
+\cs_new:Npn \@@_expandable_grab_m_aux:wNn #1 \q_@@ #2#3#4
+  { #1 {#4} \q_@@ #2 #3 }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_R:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_R_aux:NNNwNNn}
+%   Much the same as for the \texttt{D}-type argument, with only the lead-off
+%   function varying.
+%    \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_R:w #1 \q_@@ #2#3
+  { #2 { \@@_expandable_grab_R_aux:NNNwNNn #1 \q_@@ #2#3 } }
+\cs_set_protected:Npn \@@_tmp:w #1
+  {
+    \cs_new:Npn \@@_expandable_grab_R_aux:NNNwNNn ##1##2##3##4 \q_@@ ##5##6##7
+      {
+        \str_if_eq:nnTF {##7} {##2}
+          {
+            \str_if_eq:onTF
+              { ##1 { } { } ##7 ##2 \q_@@ ##3 }
+              { { } {##2} { } }
+          }
+          { \use_ii:nn }
+          {
+            ##1
+              { \@@_expandable_grab_D:NNNwNNnnn ##1##2##3##4 \q_@@ ##5##6 }
+              \q_nil { } ##2 \ERROR \q_@@ \ERROR
+          }
+          {
+            \__kernel_msg_expandable_error:nnff
+              { ltcmd } { missing-required }
+              { \exp_args:Nf \tl_trim_spaces:n { \token_to_str:N ##5 } }
+              { \tl_to_str:n {##2} }
+            ##4 {#1} \q_@@ ##5 ##6 {##7}
+          }
+      }
+  }
+\exp_args:No \@@_tmp:w { \c_novalue_tl }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_R_alt:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_R_alt_aux:NNwNNn}
+%   When the delimiters are identical, nesting is not possible and a simplified
+%   approach is used. The test concept here is the same as for the case where
+%   the delimiters are different.
+%    \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_R_alt:w #1 \q_@@ #2#3
+  { #2 { \@@_expandable_grab_R_alt_aux:NNwNNn #1 \q_@@ #2#3 } }
+\cs_set_protected:Npn \@@_tmp:w #1
+  {
+    \cs_new:Npn \@@_expandable_grab_R_alt_aux:NNwNNn ##1##2##3 \q_@@ ##4##5##6
+      {
+        \str_if_eq:nnTF {##6} {##2}
+          {
+            \str_if_eq:onTF
+              { ##1 { } ##6 ##2 ##2 }
+              { { } ##2 }
+          }
+          { \use_ii:nn }
+          {
+            ##1
+              { \@@_expandable_grab_D_alt:NNwn ##4 ##5 ##3 \q_@@ }
+              ##6 \ERROR
+          }
+          {
+            \__kernel_msg_expandable_error:nnff
+              { ltcmd } { missing-required }
+              { \exp_args:Nf \tl_trim_spaces:n { \token_to_str:N ##4 } }
+              { \tl_to_str:n {##2} }
+            ##3 {#1} \q_@@ ##4 ##5 {##6}
+          }
+      }
+  }
+\exp_args:No \@@_tmp:w { \c_novalue_tl }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_expandable_grab_t:w}
+% \begin{macro}[EXP]{\@@_expandable_grab_t_aux:NNwn}
+%   As for a \texttt{D}-type argument, here we compare the grabbed tokens using
+%   the only parser we have in order to work out if |#2| is exactly equal to
+%   the output of the grabber.
+%    \begin{macrocode}
+\cs_new:Npn \@@_expandable_grab_t:w #1 \q_@@ #2#3
+  { #2 { \@@_expandable_grab_t_aux:NNwn #1 \q_@@ #2 #3 } }
+\cs_new:Npn \@@_expandable_grab_t_aux:NNwn #1#2#3 \q_@@ #4#5#6
+  {
+    \str_if_eq:onTF { #1 { } #6 #2 } {#2}
+      { #3 { \BooleanTrue } \q_@@ #4 #5 }
+      { #3 { \BooleanFalse } \q_@@ #4 #5 {#6} }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]
+%   {\@@_put_arg_expandable:nw, \@@_put_arg_expandable:ow}
+%   A useful helper, to store arguments when they are ready.
+%    \begin{macrocode}
+\cs_new:Npn \@@_put_arg_expandable:nw #1#2 \q_@@ { #2 {#1} \q_@@ }
+\cs_generate_variant:Nn \@@_put_arg_expandable:nw { o }
+%    \end{macrocode}
+% \end{macro}
+%
+% \subsection{Argument processors}
+%
+% \begin{macro}{\@@_bool_reverse:N}
+%   A simple reversal.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_bool_reverse:N #1
+  {
+    \bool_if:NTF #1
+      { \tl_set:Nn \ProcessedArgument { \c_false_bool } }
+      { \tl_set:Nn \ProcessedArgument { \c_true_bool } }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{variable}{\l_@@_split_list_seq, \l_@@_split_list_tl}
+% \begin{macro}{\@@_split_list:nn}
+% \begin{macro}{\@@_split_list_multi:nn, \@@_split_list_multi:nV}
+% \begin{macro}{\@@_split_list_single:Nn}
+%   Splitting can take place either at a single token or at a longer
+%   identifier. To deal with single active tokens, a two-part procedure is
+%   needed.
+%    \begin{macrocode}
+\seq_new:N \l_@@_split_list_seq
+\tl_new:N \l_@@_split_list_tl
+\cs_new_protected:Npn \@@_split_list:nn #1#2
+  {
+    \tl_if_single:nTF {#1}
+      {
+        \token_if_cs:NTF #1
+          { \@@_split_list_multi:nn {#1} {#2} }
+          { \@@_split_list_single:Nn #1 {#2} }
+      }
+      { \@@_split_list_multi:nn {#1} {#2} }
+  }
+\cs_new_protected:Npn \@@_split_list_multi:nn #1#2
+  {
+    \seq_set_split:Nnn \l_@@_split_list_seq {#1} {#2}
+    \tl_clear:N \ProcessedArgument
+    \seq_map_inline:Nn \l_@@_split_list_seq
+      { \tl_put_right:Nn \ProcessedArgument { {##1} } }
+  }
+\cs_generate_variant:Nn \@@_split_list_multi:nn { nV }
+\group_begin:
+\char_set_catcode_active:N \^^@
+\cs_new_protected:Npn \@@_split_list_single:Nn #1#2
+  {
+    \tl_set:Nn \l_@@_split_list_tl {#2}
+    \group_begin:
+    \char_set_lccode:nn { `\^^@ } { `#1 }
+    \tex_lowercase:D
+      {
+        \group_end:
+        \tl_replace_all:Nnn \l_@@_split_list_tl { ^^@ }
+      }   {#1}
+     \@@_split_list_multi:nV {#1} \l_@@_split_list_tl
+   }
+\group_end:
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{variable}
+%
+% \begin{macro}{\@@_split_argument:nnn}
+% \begin{macro}{\@@_split_argument_aux:nnnn}
+% \begin{macro}[EXP]{\@@_split_argument_aux:n}
+% \begin{macro}[rEXP]{\@@_split_argument_aux:wn}
+%   Splitting to a known number of items is a special version of splitting
+%   a list, in which the limit is hard-coded and where there will always be
+%   exactly the correct number of output items. An auxiliary function is
+%   used to save on working out the token list length several times.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_split_argument:nnn #1#2#3
+  {
+    \@@_split_list:nn {#2} {#3}
+    \exp_args:Nf \@@_split_argument_aux:nnnn
+      { \tl_count:N \ProcessedArgument }
+      {#1} {#2} {#3}
+  }
+\cs_new_protected:Npn \@@_split_argument_aux:nnnn #1#2#3#4
+  {
+    \int_compare:nNnF {#1} = { #2 + 1 }
+      {
+        \int_compare:nNnTF {#1} > { #2 + 1 }
+          {
+            \tl_set:Nx \ProcessedArgument
+              {
+                \exp_last_unbraced:NnNo
+                  \@@_split_argument_aux:n
+                  { #2 + 1 }
+                  \use_none_delimit_by_q_stop:w
+                  \ProcessedArgument
+                  \q_stop
+              }
+            \__kernel_msg_error:nnxxx { ltcmd } { split-excess-tokens }
+              { \tl_to_str:n {#3} } { \int_eval:n { #2 + 1 } }
+              { \tl_to_str:n {#4} }
+          }
+          {
+            \tl_put_right:Nx \ProcessedArgument
+              {
+                \prg_replicate:nn { #2 + 1 - (#1) }
+                  { { \exp_not:V \c_novalue_tl } }
+              }
+          }
+      }
+  }
+%    \end{macrocode}
+%   Auxiliaries to leave exactly the correct number of arguments in
+%   \cs{ProcessedArgument}.
+%    \begin{macrocode}
+\cs_new:Npn \@@_split_argument_aux:n #1
+  { \prg_replicate:nn {#1} { \@@_split_argument_aux:wn } }
+\cs_new:Npn \@@_split_argument_aux:wn #1 \use_none_delimit_by_q_stop:w #2
+  {
+    \exp_not:n { {#2} }
+    #1
+    \use_none_delimit_by_q_stop:w
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_trim_spaces:n}
+%   This one is almost trivial.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_trim_spaces:n #1
+  { \tl_set:Nx \ProcessedArgument { \tl_trim_spaces:n {#1} } }
+%    \end{macrocode}
+% \end{macro}
+%
+% \subsection{Access to the argument specification}
+%
+% \begin{macro}{\@@_get_arg_spec_error:N, \@@_get_arg_spec_error:n}
+% \begin{macro}{\@@_get_arg_spec_error_aux:n}
+%   Provide an informative error when trying to get the argument
+%   specification of a non-\pkg{xparse} command or environment.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_get_arg_spec_error:N #1
+  {
+    \bool_set_false:N \l_@@_environment_bool
+    \tl_set:Nn \l_@@_fn_tl {#1}
+    \@@_get_arg_spec_error_aux:n { \cs_if_exist:NTF #1 }
+  }
+\cs_new_protected:Npn \@@_get_arg_spec_error:n #1
+  {
+    \bool_set_true:N \l_@@_environment_bool
+    \str_set:Nx \l_@@_environment_str {#1}
+    \@@_get_arg_spec_error_aux:n
+      { \cs_if_exist:cTF { \l_@@_environment_str } }
+  }
+\cs_new_protected:Npn \@@_get_arg_spec_error_aux:n #1
+  {
+    #1
+      {
+        \__kernel_msg_error:nnx { ltcmd } { non-xparse }
+          { \@@_environment_or_command: }
+      }
+      {
+        \__kernel_msg_error:nnx { ltcmd } { unknown }
+          { \@@_environment_or_command: }
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_get_arg_spec:NTF}
+%   If the command is not an \pkg{xparse} command, complain.  If it is,
+%   its second \enquote{item} is the argument specification.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_get_arg_spec:NTF #1#2#3
+  {
+    \@@_cmd_if_xparse:NTF #1
+      {
+        \tl_set:Nx \ArgumentSpecification { \tl_item:Nn #1 { 2 } }
+        #2
+      }
+      {#3}
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% Rolling forward from 2020-10-01 is tricky because the entire |ltcmd|
+% module is new, but the user-level commands have the same name, so only
+% these will clash.  To work around that, in |latexrelease| mode we will
+% (temporarily) disable \cs{__kernel_chk_if_free_cs:N} for this final
+% part of the code, then restore at the end.
+%    \begin{macrocode}
+%<latexrelease>\cs_new_eq:NN \@@_chk_if_free_cs:N \__kernel_chk_if_free_cs:N
+%<latexrelease>\cs_gset_eq:NN \__kernel_chk_if_free_cs:N \use_none:n
+%    \end{macrocode}
+%
+% \begin{variable}{\ArgumentSpecification}
+%    \begin{macrocode}
+\tl_new:N \ArgumentSpecification
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_get_arg_spec:N}
+% \begin{macro}{\@@_get_arg_spec:n}
+%   Recovering the argument specification is now trivial.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_get_arg_spec:N #1
+  {
+    \@@_get_arg_spec:NTF #1 { }
+      { \@@_get_arg_spec_error:N #1 }
+  }
+\cs_new_protected:Npn \@@_get_arg_spec:n #1
+  {
+    \exp_args:Nc \@@_get_arg_spec:NTF
+      { environment~ \tl_to_str:n {#1} }
+      { }
+      { \@@_get_arg_spec_error:n {#1} }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_show_arg_spec:N}
+% \begin{macro}{\@@_show_arg_spec:n}
+%   Showing the argument specification simply means finding it and then
+%   calling the \cs{tl_show:N} function.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_show_arg_spec:N #1
+  {
+    \@@_get_arg_spec:NTF #1
+      { \tl_show:N \ArgumentSpecification }
+      { \@@_get_arg_spec_error:N #1 }
+  }
+\cs_new_protected:Npn \@@_show_arg_spec:n #1
+  {
+    \exp_args:Nc \@@_get_arg_spec:NTF
+      { environment~ \tl_to_str:n {#1} }
+      { \tl_show:N \ArgumentSpecification }
+      { \@@_get_arg_spec_error:n {#1} }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Utilities}
+%
+% \begin{macro}{\@@_check_definable:nNT, \@@_check_definable_aux:nN}
+%   Check that a token list is appropriate as a first argument of
+%   \cs{NewDocumentCommand} and similar functions and otherwise
+%   produce an error.  First trim whitespace to allow for spaces around
+%   the actual command to be defined.  If the result has multiple
+%   tokens, it is not a valid argument.  The single token is a control
+%   sequence exactly if its string representation has more than one
+%   character (using \cs{token_to_str:N} rather than \cs{tl_to_str:n}
+%   to avoid problems with macro parameter characters, and setting
+%   \cs{tex_escapechar:D} to prevent it from being non-printable).
+%   Finally, check for an active character: this is done by lowercasing
+%   the token to fix its character code (arbitrarily to that of~|?|)
+%   and comparing the result to an active~|?|.  Both control sequences
+%   and active characters are valid arguments, and non-active character
+%   tokens are not.  In all cases, the group opened to keep assignments
+%   local must be closed.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_check_definable:nNT #1
+  { \tl_trim_spaces_apply:nN {#1} \@@_check_definable_aux:nN }
+\group_begin:
+  \char_set_catcode_active:n { `? }
+  \cs_new_protected:Npn \@@_check_definable_aux:nN #1#2
+    {
+      \group_begin:
+      \tl_if_single_token:nTF {#1}
+        {
+          \int_set:Nn \tex_escapechar:D { 92 }
+          \exp_args:Nx \tl_if_empty:nTF
+            { \exp_args:No \str_tail:n { \token_to_str:N #1 } }
+            {
+              \exp_args:Nx \char_set_lccode:nn
+                { ` \str_head:n {#1} } { `? }
+              \tex_lowercase:D { \tl_if_eq:nnTF {#1} } { ? }
+                { \group_end: \use_iii:nnn }
+                { \group_end: \use_i:nnn }
+            }
+            { \group_end: \use_iii:nnn }
+        }
+        { \group_end: \use_ii:nnn }
+      {
+        \__kernel_msg_error:nnxx { ltcmd } { not-definable }
+          { \tl_to_str:n {#1} } { \token_to_str:N #2 }
+      }
+      {
+        \__kernel_msg_error:nnxx { ltcmd } { not-one-token }
+          { \tl_to_str:n {#1} } { \token_to_str:N #2 }
+      }
+    }
+\group_end:
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_token_if_cs:NTF}
+%   Based on the definition of \cs{@@_check_definable_aux:nN} above, but
+%   only checks for an actual control sequence (\emph{i.e.},
+%   \cs[no-index]{\meta{anything}}). \cs{tex_escapechar:D} is
+%   temporarily changed to a known value and then it checks if
+%   |\string#1| contains more than one character: if it does, it's a
+%   control sequence.  This test differs from \cs{token_if_cs:NTF} for
+%   example in \verb|\token_if_cs:NTF \c_group_begin_token {T}{F}|,
+%   where \cs{token_if_cs:NTF} returns false.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_token_if_cs:NTF #1
+  {
+    \group_begin:
+      \int_set:Nn \tex_escapechar:D { 92 }
+      \exp_args:Nx \tl_if_empty:nTF
+          { \exp_args:No \str_tail:n { \token_to_str:N #1 } }
+        { \group_end: \use_ii:nn }
+        { \group_end: \use_i:nn }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_tl_mapthread_function:NNN, \@@_tl_mapthread_function:nnN}
+% \begin{macro}{\@@_tl_mapthread_loop:w}
+%   Analogue of \cs{seq_mapthread_function:NNN} for token lists.
+%    \begin{macrocode}
+\cs_new:Npn \@@_tl_mapthread_function:NNN #1#2#3
+  {
+    \exp_after:wN \exp_after:wN
+    \exp_after:wN \@@_tl_mapthread_loop:w
+    \exp_after:wN \exp_after:wN
+    \exp_after:wN #3
+    \exp_after:wN #1
+    \exp_after:wN \q_recursion_tail
+    \exp_after:wN \q_mark
+    #2
+    \q_recursion_tail
+    \q_recursion_stop
+  }
+\cs_new:Npn \@@_tl_mapthread_function:nnN #1#2#3
+  {
+    \@@_tl_mapthread_loop:w #3
+      #1 \q_recursion_tail \q_mark
+      #2 \q_recursion_tail \q_recursion_stop
+  }
+\cs_new:Npn \@@_tl_mapthread_loop:w #1#2#3 \q_mark #4
+  {
+    \quark_if_recursion_tail_stop:n {#2}
+    \quark_if_recursion_tail_stop:n {#4}
+    #1 {#2} {#4}
+    \@@_tl_mapthread_loop:w #1#3 \q_mark
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_cmd_if_xparse:NTF}
+% \begin{macro}{\@@_cmd_if_xparse_aux:N}
+%   To determine whether the command is an \pkg{xparse} command check
+%   that its |arg_spec| is empty (this also excludes non-macros) and
+%   that its |replacement_spec| starts with either \cs{@@_start:nNNnnn}
+%   (non-expandable command) or \cs{@@_start_expandable:nNNNNn}
+%   (expandable command) or \cs{@@_start_env:nnnnn} (environment).
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_cmd_if_xparse:NTF #1
+  {
+    \exp_args:Nf \str_case_e:nnTF
+      {
+        \exp_args:Nf \tl_if_empty:nT { \cs_argument_spec:N #1 }
+          {
+            \exp_last_unbraced:Nf \@@_cmd_if_xparse_aux:w
+              { \cs_replacement_spec:N #1 } ~ \q_stop
+          }
+      }
+      {
+        { \token_to_str:N \@@_start:nNNnnn } { }
+        { \token_to_str:N \@@_start_expandable:nNNNNn } { }
+        { \token_to_str:N \@@_start_env:nnnnn } { }
+      }
+  }
+\cs_new:Npn \@@_cmd_if_xparse_aux:w #1 ~ #2 \q_stop {#1}
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_peek_nonspace:NTF, \@@_peek_nonspace_remove:NTF, \@@_peek_nonspace_aux:nNNTF}
+%   Collect spaces in a loop, and put the collected spaces back in the
+%   false branch of a call to \cs{peek_meaning:NTF} or
+%   \cs{peek_meaning_remove:NTF}.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_peek_nonspace:NTF
+  { \@@_peek_nonspace_aux:nNNTF { } \@@_peek_meaning:NTF }
+\cs_new_protected:Npn \@@_peek_nonspace_remove:NTF
+  { \@@_peek_nonspace_aux:nNNTF { } \@@_peek_meaning_remove:NTF }
+\cs_new_protected:Npn \@@_peek_nonspace_aux:nNNTF #1#2#3#4#5
+  {
+    \peek_meaning_remove:NTF \c_space_token
+      { \@@_peek_nonspace_aux:nNNTF { #1 ~ } #2 #3 {#4} {#5} }
+      { #2 #3 { #4 } { #5 #1 } }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_peek_meaning:NTF, \@@_peek_meaning_remove:NTF}
+% \begin{macro}{\@@_peek_cs_check_equal:NNN, \@@_peek_meaning_aux:NNTF, \@@_peek_true_remove:NNw}
+%   Peek ahead for a token with a given meaning.  In case the search
+%   token is a control sequence, also check that the \meta{csname} is
+%   the same as the control sequence peeked at.  This extra verification
+%   is necessary when the command is delimited by control sequence tokens
+%   (as opposed to character tokens), and we want the the exact same
+%   control sequence to match.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_peek_meaning:NTF
+  { \@@_peek_meaning_aux:NNTF \c_false_bool }
+\cs_new_protected:Npn \@@_peek_meaning_remove:NTF
+  { \@@_peek_meaning_aux:NNTF \c_true_bool }
+\cs_new_protected:Npn \@@_peek_meaning_aux:NNTF #1#2#3#4
+  {
+    \tl_set:Nn \l_@@_tmpa_tl {#3}
+    \tl_set:Nn \l_@@_tmpb_tl {#4}
+    \peek_meaning:NTF #2
+      {
+        \token_if_eq_meaning:NNTF #2 \c_group_begin_token
+          { \@@_peek_true_remove:Nw #1 }
+          {
+            \@@_token_if_cs:NTF #2
+              { \@@_peek_cs_check_equal:NNN #1 #2 }
+              { \@@_peek_true_remove:Nw #1 }
+          }
+      }
+      { \l_@@_tmpb_tl }
+  }
+\cs_new_protected:Npn \@@_peek_cs_check_equal:NNN #1#2#3
+  {
+    \str_if_eq:nnTF {#2} {#3}
+      { \@@_peek_true_remove:Nw #1 }
+      { \l_@@_tmpb_tl }
+    #3
+  }
+\cs_new_protected:Npn \@@_peek_true_remove:Nw #1
+  {
+    \bool_if:NTF #1
+      {
+        \tex_afterassignment:D \l_@@_tmpa_tl
+        \cs_set_eq:NN \@@_tmp:w
+      }
+      { \l_@@_tmpa_tl }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \subsection{Messages}
+%
+% \begin{variable}{\c_@@_ignore_def_tl}
+%    \begin{macrocode}
+\tl_const:Nn \c_@@_ignore_def_tl
+  { \\ \\ LaTeX~will~ignore~this~entire~definition. }
+%    \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_environment_or_command:}
+%   Two texts used in several messages.
+%    \begin{macrocode}
+\cs_new:Npn \@@_environment_or_command:
+  {
+    \bool_if:NTF \l_@@_environment_bool
+      { environment ~ ' \l_@@_environment_str ' }
+      {
+        command ~ '
+        \exp_args:Nf \tl_trim_spaces:n
+          { \exp_after:wN \token_to_str:N \l_@@_fn_tl }
+        '
+      }
+  }
+%    \end{macrocode}
+% \end{macro}
+%
+% Some messages intended as errors when defining commands/environments.
+%    \begin{macrocode}
+\__kernel_msg_new:nnnn { ltcmd } { arg-after-body }
+  { In~the~definition~of~#1,~b~(body)~argument~must~be~last. }
+  {
+    The~'body'~argument~type~is~followed~by~'#2'~in~the~argument~
+    specification~of~the~#1.~This~is~not~allowed.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { bad-arg-spec }
+  { Bad~argument~specification~'#2'~for~#1. }
+  {
+    The~argument~specification~provided~was~not~valid:~
+    one~or~more~mandatory~pieces~of~information~were~missing.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { command-already-defined }
+  { Command~'#1'~already~defined! }
+  {
+    You~have~used~#2~
+    with~a~command~that~already~has~a~definition. \\ \\
+    The~existing~definition~of~'#1'~will~not~be~altered.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { command-not-yet-defined }
+  { Command ~'#1'~not~yet~defined! }
+  {
+    You~have~used~#2~
+    with~a~command~that~was~never~defined.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { environment-already-defined }
+  { Environment~'#1'~already~defined! }
+  {
+    You~have~used~\NewDocumentEnvironment
+    with~an~environment~that~already~has~a~definition. \\ \\
+    The~existing~definition~of~'#1'~will~not~be~altered.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { environment-not-yet-defined }
+  { Environment~'#1'~not~yet~defined! }
+  {
+    You~have~used~\RenewDocumentEnvironment
+    with~an~environment~that~was~never~defined.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { expandable-ending-optional }
+  {
+    Argument~specification~'#2'~for~expandable~command~'#1'~
+    ends~with~optional~argument.
+  }
+  {
+    Expandable~commands~must~have~a~final~mandatory~argument~
+    (or~no~arguments~at~all).~You~cannot~have~a~terminal~optional~
+    argument~with~expandable~commands.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { inconsistent-long }
+  { Inconsistent~long~arguments~for~expandable~command~'#1'. }
+  {
+    The~arguments~for~an~expandable~command~must~not~involve~short~
+    arguments~after~long~arguments.~You~have~tried~to~mix~the~two~types.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { invalid-command-arg }
+  { Argument~type~'#2'~not~available~for~#1. }
+  {
+    The~letter~'#2'~can~only~be~used~in~environment~argument~
+    specifications,~not~for~commands.
+    \\ \\
+    LaTeX~will~ignore~this~entire~definition.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { invalid-expandable-argument-type }
+  { Argument~type~'#2'~not~available~for~expandable~command~'#1'. }
+  {
+    The~letter~'#2'~specifies~an~argument~type~which~cannot~be~used~
+    in~an~expandable~command.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { invalid-after-optional-expandably }
+  {
+    Argument~type~'#2'~not~available~after~optional~argument~
+    for~expandable~command~'#1'.
+  }
+  {
+    The~letter~'#2'~specifies~an~argument~type~which~cannot~be~used~
+    in~an~expandable~command~after~an~optional~argument.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { non-trailing-obey-spaces }
+  { Prefix~'!'~used~before~mandatory~argument~'#2'~of~#1. }
+  {
+    The~prefix~'!'~can~only~apply~to~trailing~optional~arguments.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { not-definable }
+  { First~argument~of~'#2'~must~be~a~command. }
+  {
+    The~first~argument~of~'#2'~should~be~the~document~command~that~will~
+    be~defined.~The~provided~argument~'#1'~is~a~character.~Perhaps~a~
+    backslash~is~missing?
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { not-one-token }
+  { First~argument~of~'#2'~must~be~a~command. }
+  {
+    The~first~argument~of~'#2'~should~be~the~document~command~that~will~
+    be~defined.~The~provided~argument~'#1'~contains~more~than~one~
+    token.~Perhaps~a~backslash~is~missing?
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { not-single-token }
+  {
+    Argument~delimiter~'#2'~for~the~#1~should~be~
+    a~single~non-space~token.
+  }
+  {
+    The~argument~specification~provided~was~not~valid:~in~a~place~
+    where~a~single~token~is~required,~LaTeX~found~'#2'.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { forbidden-implicit-group-token }
+  { Argument~delimiter~'#2'~for~the~#1~is~not~allowed. }
+  {
+    The~argument~specification~provided~was~not~valid:~the~implicit~
+    #3-group~token~'#2'~is~not~allowed~as~an~argument~delimiter.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { processor-in-expandable }
+  { Argument~processor~'>{#2}'~cannot~be~used~for~the~expandable~command~'#1'. }
+  {
+    The~argument~specification~for~#1~contains~a~processor~function:~
+    this~is~only~supported~for~standard~robust~commands.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { too-many-arguments }
+  { Too~many~arguments~in~argument~specification~'#2'~of~#1. }
+  {
+    The~argument~specification~provided~has~more~than~9~arguments.~
+    This~cannot~be~implemented.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { two-markers }
+  { Two~'#2'~apply~to~the~same~argument~in~argument~specification~of~#1. }
+  {
+    The~argument~specification~provided~has~two~markers~'#2'~applying~
+    to~the~same~argument;~these~are~redundant.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { unknown-argument-type }
+  { Unknown~argument~type~'#2'~for~the~#1. }
+  {
+    The~letter~'#2'~does~not~specify~a~known~argument~type.
+    \c_@@_ignore_def_tl
+  }
+\__kernel_msg_new:nnnn { ltcmd } { xparse-argument-type }
+  { Deprecated~argument~type~'#2'~for~the~#1~requires~xparse. }
+  {
+    The~letter~'#2'~specifies~a~known~argument~type~that~requires~
+    the~xparse~package.
+    \c_@@_ignore_def_tl
+  }
+%    \end{macrocode}
+%
+% Errors when using commands/environments.  The \texttt{if-boolean}
+% message is always used in expandable errors.  The
+% \texttt{loop-in-defaults} and \texttt{missing-required} messages can
+% be expandable or not expandable.
+%    \begin{macrocode}
+\__kernel_msg_new:nnn { ltcmd } { if-boolean }
+  { Invalid~use~\iow_char:N\\IfBooleanTF~{#1} }
+\__kernel_msg_new:nnnn { ltcmd } { loop-in-defaults }
+  { Defaults~of~#1~have~circular~dependency. }
+  {
+    The~default~values~of~two~or~more~arguments~of~the~#1~
+    depend~on~each~other~in~a~way~that~cannot~be~resolved.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { missing-required }
+  { Missing~required~argument~for~#1. }
+  {
+    The~current~#1~expects~an~argument~starting~with~'#2'.~
+    LaTeX~did~not~find~it,~and~will~insert~a~default~value~to~be~processed.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { non-xparse }
+  { \str_uppercase:n #1~not~defined~using~xparse. }
+  {
+    You~have~asked~for~the~argument~specification~for~the~#1,~
+    but~this~was~not~defined~using~xparse.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { split-excess-tokens }
+  { Too~many~'#1'~tokens~when~trying~to~split~argument. }
+  {
+    LaTeX~was~asked~to~split~the~input~'#3'~
+    at~each~occurrence~of~the~token~'#1',~up~to~a~maximum~of~#2~parts.~
+    There~were~too~many~'#1'~tokens.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { unknown }
+  { Unknown~document~#1. }
+  {
+    You~have~asked~for~the~argument~specification~for~the~#1,~
+    but~it~is~not~defined.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { verbatim-newline }
+  { Verbatim~argument~of~#1~ended~by~end~of~line. }
+  {
+    The~verbatim~argument~of~the~#1~cannot~contain~more~than~one~line,~
+    but~the~end~
+    of~the~current~line~has~been~reached.~You~may~have~forgotten~the~
+    closing~delimiter.
+    \\ \\
+    LaTeX~will~ignore~'#2'.
+  }
+\__kernel_msg_new:nnnn { ltcmd } { verbatim-tokenized }
+  { The~verbatim~#1~cannot~be~used~inside~an~argument. }
+  {
+    The~#1~takes~a~verbatim~argument.~
+    It~may~not~appear~within~the~argument~of~another~function.~
+    It~received~an~illegal~token \tl_if_empty:nF {#3} { ~'#3' } .
+    \\ \\
+    LaTeX~will~ignore~'#2'.
+  }
+%    \end{macrocode}
+%
+% Intended more for information.
+%    \begin{macrocode}
+\__kernel_msg_new:nnn { ltcmd } { define-command }
+  {
+    Defining~command~#1~
+    with~sig.~'#2'~\msg_line_context:.
+  }
+\__kernel_msg_new:nnn { ltcmd } { define-environment }
+  {
+    Defining~environment~'#1'~
+    with~sig.~'#2'~\msg_line_context:.
+  }
+\__kernel_msg_new:nnn { ltcmd } { redefine-command }
+  {
+    Redefining~command~#1~
+    with~sig.~'#2'~\msg_line_context:.
+  }
+\__kernel_msg_new:nnn { ltcmd } { redefine-environment }
+  {
+    Redefining~environment~'#1'~
+    with~sig.~'#2'~\msg_line_context:.
+  }
+\__kernel_msg_new:nnn { ltcmd } { optional-mandatory }
+  {
+    Since~the~mandatory~argument~'#1'~has~the~same~delimiter~'#2'~
+    as~a~previous~optional~argument,~it~will~not~be~possible~to~
+    omit~all~optional~arguments~when~calling~this~command.
+  }
+\__kernel_msg_new:nnn { ltcmd } { unsupported-let }
+  {
+    The~command~'#1'~was~undefined~but~not~the~associated~commands~
+    '#1~code'~and/or~'#1~defaults'.~Maybe~you~tried~using~
+    \iow_char:N\\let.~This~may~lead~to~an~infinite~loop.
+  }
+%    \end{macrocode}
+%
+% \subsection{User functions}
+%
+% The user functions are more or less just the internal functions
+% renamed.
+%
+% \begin{macro}{\BooleanFalse}
+% \begin{macro}{\BooleanTrue}
+%   Design-space names for the Boolean values.
+%    \begin{macrocode}
+\cs_new_eq:NN \BooleanFalse \c_false_bool
+\cs_new_eq:NN \BooleanTrue  \c_true_bool
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\NewDocumentCommand}
+% \begin{macro}{\RenewDocumentCommand}
+% \begin{macro}{\ProvideDocumentCommand}
+% \begin{macro}{\DeclareDocumentCommand}
+%   The user macros are pretty simple wrappers around the internal ones.
+%   There is however a check that the first argument is a single token,
+%   possibly surrounded by spaces (hence the strange \cs{use:nnn}), and
+%   is definable.
+%    \begin{macrocode}
+\cs_new_protected:Npn \NewDocumentCommand #1#2#3
+  {
+    \@@_check_definable:nNT {#1} \NewDocumentCommand
+      {
+        \cs_if_exist:NTF #1
+          {
+            \__kernel_msg_error:nnxx { ltcmd } { command-already-defined }
+              { \use:nnn \token_to_str:N #1 { } }
+              { \token_to_str:N \NewDocumentCommand }
+          }
+          { \@@_declare_cmd:Nnn #1 {#2} {#3} }
+      }
+  }
+\cs_new_protected:Npn \RenewDocumentCommand #1#2#3
+  {
+    \@@_check_definable:nNT {#1} \RenewDocumentCommand
+      {
+        \cs_if_exist:NTF #1
+          { \@@_declare_cmd:Nnn #1 {#2} {#3} }
+          {
+            \__kernel_msg_error:nnxx { ltcmd } { command-not-yet-defined }
+              { \use:nnn \token_to_str:N #1 { } }
+              { \token_to_str:N \RenewDocumentCommand }
+          }
+      }
+  }
+\cs_new_protected:Npn \ProvideDocumentCommand #1#2#3
+  {
+    \@@_check_definable:nNT {#1} \ProvideDocumentCommand
+      { \cs_if_exist:NF #1 { \@@_declare_cmd:Nnn #1 {#2} {#3} } }
+ }
+\cs_new_protected:Npn \DeclareDocumentCommand #1#2#3
+  {
+    \@@_check_definable:nNT {#1} \DeclareDocumentCommand
+      { \@@_declare_cmd:Nnn #1 {#2} {#3} }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\NewDocumentEnvironment}
+% \begin{macro}{\RenewDocumentEnvironment}
+% \begin{macro}{\ProvideDocumentEnvironment}
+% \begin{macro}{\DeclareDocumentEnvironment}
+%   Very similar for environments.
+%    \begin{macrocode}
+\cs_new_protected:Npn \NewDocumentEnvironment #1#2#3#4
+  {
+    \cs_if_exist:cTF {#1}
+      { \__kernel_msg_error:nnx { ltcmd } { environment-already-defined } {#1} }
+      { \@@_declare_env:nnnn {#1} {#2} {#3} {#4} }
+  }
+\cs_new_protected:Npn \RenewDocumentEnvironment #1#2#3#4
+  {
+    \cs_if_exist:cTF {#1}
+      { \@@_declare_env:nnnn {#1} {#2} {#3} {#4} }
+      { \__kernel_msg_error:nnx { ltcmd } { environment-not-yet-defined } {#1} }
+  }
+\cs_new_protected:Npn \ProvideDocumentEnvironment #1#2#3#4
+  { \cs_if_exist:cF {#1} { \@@_declare_env:nnnn {#1} {#2} {#3} {#4} } }
+\cs_new_protected:Npn \DeclareDocumentEnvironment #1#2#3#4
+  { \@@_declare_env:nnnn {#1} {#2} {#3} {#4} }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\NewExpandableDocumentCommand}
+% \begin{macro}{\RenewExpandableDocumentCommand}
+% \begin{macro}{\ProvideExpandableDocumentCommand}
+% \begin{macro}{\DeclareExpandableDocumentCommand}
+%   The expandable versions are essentially the same as the basic
+%   functions.  The strange \cs{use:nnn} is there in case |#1| is
+%   surrounded with spaces, as can happen with usual document catcodes
+%   in \cs{RenewExpandableDocumentCommand} |{| |\!| |}| \ldots{}
+%    \begin{macrocode}
+\cs_new_protected:Npn \NewExpandableDocumentCommand #1#2#3
+  {
+    \@@_check_definable:nNT {#1} \NewExpandableDocumentCommand
+      {
+        \cs_if_exist:NTF #1
+          {
+            \__kernel_msg_error:nnxx { ltcmd } { command-already-defined }
+              { \use:nnn \token_to_str:N #1 { } }
+              { \token_to_str:N \NewExpandableDocumentCommand }
+          }
+          { \@@_declare_expandable_cmd:Nnn #1 {#2} {#3} }
+      }
+  }
+\cs_new_protected:Npn \RenewExpandableDocumentCommand #1#2#3
+  {
+    \@@_check_definable:nNT {#1} \RenewExpandableDocumentCommand
+      {
+        \cs_if_exist:NTF #1
+          { \@@_declare_expandable_cmd:Nnn #1 {#2} {#3} }
+          {
+            \__kernel_msg_error:nnxx { ltcmd } { command-not-yet-defined }
+              { \use:nnn \token_to_str:N #1 { } }
+              { \token_to_str:N \RenewExpandableDocumentCommand }
+          }
+      }
+  }
+\cs_new_protected:Npn \ProvideExpandableDocumentCommand #1#2#3
+  {
+    \@@_check_definable:nNT {#1} \ProvideExpandableDocumentCommand
+      {
+        \cs_if_exist:NF #1
+          { \@@_declare_expandable_cmd:Nnn #1 {#2} {#3} }
+      }
+ }
+\cs_new_protected:Npn \DeclareExpandableDocumentCommand #1#2#3
+  {
+    \@@_check_definable:nNT {#1} \DeclareExpandableDocumentCommand
+      { \@@_declare_expandable_cmd:Nnn #1 {#2} {#3} }
+  }
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\IfBooleanT, \IfBooleanF, \IfBooleanTF}
+%   The logical \meta{true} and \meta{false} statements are just the
+%   normal \cs{c_true_bool} and \cs{c_false_bool} so \cs{bool_if:NTF} is
+%   almost enough.  However, this code-level function blows up badly
+%   when passed invalid input.  We want \cs{IfBooleanTF} to accept a
+%   single (non-space) token equal to \cs{c_true_bool} or
+%   \cs{c_false_bool}, possibly surrounded by spaces.  If the input is
+%   blank or multiple items, jump to the error and pick the false
+%   branch.  If the input, ignoring spaces (we do this by omitting
+%   braces in the \cs{tl_if_single_token:nF} test), is not a single
+%   token then jump to the error as well.  It is then safe to compare
+%   the token to the two booleans, picking the appropriate branch.  If
+%   neither matches, we jump to the error as well.
+%    \begin{macrocode}
+\cs_new:Npn \IfBooleanTF #1
+  {
+    \tl_if_single:nF {#1}
+      { \prg_break:n { \use:n } }
+    \tl_if_single_token:nF #1
+      { \prg_break:n { \use:n } }
+    \token_if_eq_meaning:NNT #1 \c_true_bool
+      { \prg_break:n { \use_ii:nnn } }
+    \token_if_eq_meaning:NNT #1 \c_false_bool
+      { \prg_break:n { \use_iii:nnn } }
+    \prg_break:n { \use:n }
+    \prg_break_point:
+    {
+      \__kernel_msg_expandable_error:nnn { ltcmd } { if-boolean } {#1}
+      \use_ii:nn
+    }
+  }
+\cs_new:Npn \IfBooleanT #1#2 { \IfBooleanTF {#1} {#2} { } }
+\cs_new:Npn \IfBooleanF #1 { \IfBooleanTF {#1} { } }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\IfNoValueT, \IfNoValueF, \IfNoValueTF}
+%   Simple re-naming.
+%    \begin{macrocode}
+\cs_new_eq:NN \IfNoValueF  \tl_if_novalue:nF
+\cs_new_eq:NN \IfNoValueT  \tl_if_novalue:nT
+\cs_new_eq:NN \IfNoValueTF \tl_if_novalue:nTF
+%    \end{macrocode}
+% \end{macro}
+% \begin{macro}{\IfValueT, \IfValueF, \IfValueTF}
+%   Inverted logic.
+%    \begin{macrocode}
+\cs_new:Npn \IfValueF { \tl_if_novalue:nT }
+\cs_new:Npn \IfValueT { \tl_if_novalue:nF }
+\cs_new:Npn \IfValueTF #1#2#3 { \tl_if_novalue:nTF {#1} {#3} {#2} }
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\ProcessedArgument}
+%   Processed arguments are returned using this name, which is reserved
+%   here although the definition will change.
+%    \begin{macrocode}
+\tl_new:N \ProcessedArgument
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\ReverseBoolean, \SplitArgument, \SplitList, \TrimSpaces}
+%   Simple copies.
+%    \begin{macrocode}
+\cs_new_eq:NN \ReverseBoolean \@@_bool_reverse:N
+\cs_new_eq:NN \SplitArgument  \@@_split_argument:nnn
+\cs_new_eq:NN \SplitList      \@@_split_list:nn
+\cs_new_eq:NN \TrimSpaces     \@@_trim_spaces:n
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\ProcessList}
+%   To support \cs{SplitList}.
+%    \begin{macrocode}
+\cs_new_eq:NN \ProcessList \tl_map_function:nN
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\GetDocumentCommandArgSpec}
+% \begin{macro}{\GetDocumentEnvironmentArgSpec}
+% \begin{macro}{\ShowDocumentCommandArgSpec}
+% \begin{macro}{\ShowDocumentEnvironmentArgSpec}
+%   More simple mappings, with a check that the argument is a single
+%   control sequence or active character.
+%    \begin{macrocode}
+\cs_new_protected:Npn \GetDocumentCommandArgSpec #1
+  {
+    \@@_check_definable:nNT {#1} \GetDocumentCommandArgSpec
+      { \@@_get_arg_spec:N #1 }
+  }
+\cs_new_eq:NN \GetDocumentEnvironmentArgSpec \@@_get_arg_spec:n
+\cs_new_protected:Npn \ShowDocumentCommandArgSpec #1
+  {
+    \@@_check_definable:nNT {#1} \ShowDocumentCommandArgSpec
+      { \@@_show_arg_spec:N #1 }
+  }
+\cs_new_eq:NN \ShowDocumentEnvironmentArgSpec \@@_show_arg_spec:n
+%    \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% Finally as promised, restore \cs{__kernel_chk_if_free_cs:N}:
+%    \begin{macrocode}
+%<latexrelease>\cs_gset_eq:NN \__kernel_chk_if_free_cs:N \@@_chk_if_free_cs:N
+%<latexrelease>\cs_undefine:N \@@_chk_if_free_cs:N
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\ExplSyntaxOff
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+%</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%<latexrelease>\catcode`\^^@=\@latexrelease@catcode@null\relax
+%<latexrelease>
+%<latexrelease>\IncludeInRelease{2020/10/01}%
+%<latexrelease>                 {\NewDocumentCommand}{Document commands}%
+%<latexrelease>\@ifundefined{NewDocumentCommand}
+%<latexrelease>  {%
+%<latexrelease>    \IfFileExists{xparse.ltx}
+%<latexrelease>      {\input xparse.ltx }
+%<latexrelease>      {\@latex@error{LaTeX requires xparse}\@ehd}%
+%<latexrelease>  }
+%<latexrelease>  {}
+%<latexrelease>\EndIncludeInRelease
+%<latexrelease>
+%<latexrelease>\IncludeInRelease{0000/00/00}%
+%<latexrelease>                 {\NewDocumentCommand}{Document commands}%
+%<latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%    \end{macrocode}
+%
+% We need to stop DocStrip treating |@@| in a special way at this point.
+%    \begin{macrocode}
+%<@@=>
+%    \end{macrocode}
+%
+% \Finale
diff --git a/Master/texmf-dist/source/latex-dev/base/ltcntrl.dtx b/Master/texmf-dist/source/latex-dev/base/ltcntrl.dtx
index a9357a06b87..d65b3aee94f 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltcntrl.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltcntrl.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltcounts.dtx b/Master/texmf-dist/source/latex-dev/base/ltcounts.dtx
index 121979116c9..445cac2f2e4 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltcounts.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltcounts.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltdefns.dtx b/Master/texmf-dist/source/latex-dev/base/ltdefns.dtx
index aff93510f97..ab9d4d0da16 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltdefns.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltdefns.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -32,7 +32,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltdefns.dtx}
-             [2020/11/25 v1.5o LaTeX Kernel (definition commands)]
+             [2021/01/15 v1.5o LaTeX Kernel (definition commands)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltdefns.dtx}
@@ -1471,7 +1471,7 @@
 %     \ldots
 %   \end{quote}
 %   \cs{robust@command@act} will iterate over the \meta{action-list}, evaluating
-%   each \meta{if-type-$n$}\meta{robust-cmd}|{|\meta{true}|}{|\meta{false}|}|.
+%   each \meta{if-type-$n$} \meta{robust-cmd} |{|\meta{true}|}{|\meta{false}|}|.
 %   If the \meta{if-type-$n$} conditional returns \meta{true}, then
 %   \meta{act-type-$n$}\meta{act-arg} is executed, and the loop ends.  If the
 %   conditional returns \meta{false}, then \meta{if-type-$n+1$} is executed in
diff --git a/Master/texmf-dist/source/latex-dev/base/ltdirchk.dtx b/Master/texmf-dist/source/latex-dev/base/ltdirchk.dtx
index 0e85f0a4052..36a1ca616cd 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltdirchk.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltdirchk.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -37,7 +37,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltdirchk.dtx}
-             [2020/12/05 v1.3a LaTeX Kernel (System Dependent Parts)]
+             [2021/01/15 v1.3a LaTeX Kernel (System Dependent Parts)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltdirchk.dtx}
@@ -127,14 +127,16 @@
 % |\input@path| should expand to a list of such directories, each in a
 % |{}| group.
 %
+% \begin{sloppypar}
 % \DescribeMacro{\filename@parse}
 % After a call of the form: |\filename@parse{|\meta{filename}|}|, the
-% three macros |\filename@area|,|\filename@base|,|\filename@ext| should
+% three macros |\filename@area|, |\filename@base| and |\filename@ext| should
 % be defined to be the `area' (or directory), basename and
 % extension respectively. If there was no extension specified in
 % \meta{filename}, |\filename@ext| should be |\let| to |\relax| (so this
 % case may be tested with |\@ifundefined{filename@ext}| and, perhaps a
 % default extension substituted).
+% \end{sloppypar}
 %
 % Normally one would not need to define this macro in |texsys.cfg| as
 % the automatic tests can supply parsers that work with UNIX and VMS and
@@ -470,14 +472,16 @@
 % |{}| group.
 %
 %
+% \begin{sloppypar}
 % \DescribeMacro{\filename@parse}
 % After a call of the form: |\filename@parse{|\meta{filename}|}|, the
-% three macros |\filename@area|,|\filename@base|,|\filename@ext| should
+% three macros |\filename@area|, |\filename@base|, |\filename@ext| should
 % be defined to be the `area' (or directory), basename and
 % extension respectively. If there was no extension specified in
 % \meta{filename}, |\filename@ext| should be |\let| to |\relax| (so this
 % case may be tested with |\@ifundefined{filename@ext}| and, perhaps a
 % default extension substituted).
+% \end{sloppypar}
 %
 % Normally one would not need to define this macro in |texsys.cfg| as
 % the automatic tests can supply parsers that work with UNIX and VMS
diff --git a/Master/texmf-dist/source/latex-dev/base/lterror.dtx b/Master/texmf-dist/source/latex-dev/base/lterror.dtx
index 91d221bced3..7f480a0171f 100644
--- a/Master/texmf-dist/source/latex-dev/base/lterror.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/lterror.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltexpl.dtx b/Master/texmf-dist/source/latex-dev/base/ltexpl.dtx
index b642fd72a39..a9be1b05211 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltexpl.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltexpl.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 2019-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -33,7 +33,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltexpl.dtx}
-             [2020/12/18 v1.2h LaTeX Kernel (expl3-dependent code)]
+             [2021/01/24 v1.3a LaTeX Kernel (expl3-dependent code)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltexpl.dtx}
@@ -101,14 +101,16 @@
 % First define some blank commands, so that in case something goes wrong while
 % loading \textsf{expl3}, we won't get strange \texttt{Undefined control
 % sequence} errors.
+% \changes{v1.3a}{2021/01/24}{Define \pkg{expl3} hooks conditionally}
 %    \begin{macrocode}
 %<*2ekernel|latexrelease>
 %<latexrelease>\IncludeInRelease{2020/10/01}%
 %<latexrelease>            {\@expl@sys@load@backend@@}{Roll forward support}%
-\def\@expl@sys@load@backend@@{}
-\def\@expl@push@filename@@{}
-\def\@expl@push@filename@aux@@{}
-\def\@expl@pop@filename@@{}
+\def\reserved@a#1{\ifdefined#1\else\def#1{}\fi}
+\reserved@a\@expl@sys@load@backend@@
+\reserved@a\@expl@push@filename@@
+\reserved@a\@expl@push@filename@aux@@
+\reserved@a\@expl@pop@filename@@
 %<latexrelease>\EndIncludeInRelease
 %</2ekernel|latexrelease>
 %    \end{macrocode}
@@ -188,7 +190,9 @@
 % In \texttt{2ekernel} mode, an error is fatal and building the format
 % is aborted. Use \verb=\batchmode \read -1 to \tokenlist=, which errors
 % with
-% \verb=! Emergency stop. (cannot \read from terminal in nonstop modes)=
+%\begin{verbatim}
+%   ! Emergency stop. (cannot \read from terminal in nonstop modes)
+%\end{verbatim}
 % and aborts the \TeX{} run.  In \texttt{latexrelease} mode, raise an
 % error and do nothing.  Both ways, the error message shows the minimum
 % \textsf{expl3} engine requirements.
@@ -214,7 +218,7 @@
 %</2ekernel>
 %    \end{macrocode}
 %    We do not support a roll forward across 2019. You need to start
-%    with 2019 if you want to get to 2020 or beyond. 
+%    with 2019 if you want to get to 2020 or beyond.
 % \changes{v1.2g}{2020/11/24}{Support for roll forward (gh/434)}
 %    \begin{macrocode}
 %<*latexrelease>
@@ -225,21 +229,18 @@
            --- I'm giving up!\MessageBreak\MessageBreak
            Note that manually loading the expl3 package\MessageBreak
            from your distribution is not enough}%
-        \@@end  % die
+        \batchmode \read -1 to \reserved@a
 %</latexrelease>
       }%
-      {%
-        \input expl3.ltx
-        \ifdefined\NewDocumentCommand
-        \else
-          \IfFileExists{xparse.ltx}
-            {\input xparse.ltx }
-            {}%
-         \fi
-      }%
+      {\input expl3.ltx }%
   }
 %<latexrelease>\EndIncludeInRelease
 %<latexrelease>
+%    \end{macrocode}
+% To support roll-forward for the case where \textsf{xparse} is fully
+% integrated into the kernel, we do not need to repeat the complex test
+% above as we can simply look for the marker command.
+%    \begin{macrocode}
 %<latexrelease>\IncludeInRelease{2020/02/02}%
 %<latexrelease>                 {expl3}{Pre-load expl3}%
 %<latexrelease>\IfFileExists{expl3.ltx}
@@ -262,35 +263,8 @@
 %<latexrelease>\EndIncludeInRelease
 %    \end{macrocode}
 %
-%
-%    Starting with 2020-10 the kernel contains most of the
-%    \texttt{xparse} interfaces loaded above. These interfaces are
-%    later used to define various user command. However, if somebody
-%    with an earlier installation tries to roll forward (using a
-%    \texttt{latexrelease} package from a newer release) this will not
-%    work as the earlier kernel doesn't contain commands such as
-%    \cs{NewDocumentCommand}.
-%
-%    We therefore add code into \texttt{latexrelease.sty} to load the
-%    \texttt{xparse} package of the current installation instead. this
-%    may not work if the installation is really old, but roll forward
-%    can't do miracles.
-%
-%    If the kernel is 2020-10 or later \cs{NewDocumentCommand} is
-%    already known (whether or not you roll forward or back) so
-%    nothing happens, but if you start from am earlier kernel the
-%    \texttt{xparse} package gets loaded by \texttt{latexrelease}.
-% \changes{v1.2g}{2020/11/24}{Load xparse in latexrelease if needed (gh/434)}
-%    \begin{macrocode}
-%<latexrelease>\IncludeInRelease{2020/10/01}%
-%<latexrelease>                 {\NewDocumentCommand}{Emergency loading xparse}%
-%<latexrelease>
-%<latexrelease>\ifdefined\NewDocumentCommand \else
-%<latexrelease>  \RequirePackage{xparse}
-%<latexrelease>\fi
-%<latexrelease>
-%<latexrelease>\EndIncludeInRelease
-%    \end{macrocode}
+% \changes{v1.3a}{2021/01/21}
+%                {Move \pkg{xparse} rollback code to \texttt{ltcmd.dtx}}
 %
 %    \subsection{Using expl3 code}
 %
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfilehook.dtx b/Master/texmf-dist/source/latex-dev/base/ltfilehook.dtx
index b5b5de629a6..85c758ae608 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfilehook.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfilehook.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
-%%
-%% File: ltfilehook.dtx (C) Copyright 2020,2021 Frank Mittelbach,
-%%                                         Phelype Oleinik & LaTeX Team
+%
+% Copyright (C) 2020-2021
+%     Frank Mittelbach, Phelype Oleinik & LaTeX Team
 %
 % This file is part of the LaTeX base system.
 % -------------------------------------------
@@ -31,8 +31,8 @@
 %%% From File: ltfilehook.dtx
 %
 %    \begin{macrocode}
-\providecommand\ltfilehookversion{v1.0e}
-\providecommand\ltfilehookdate{2021/01/07}
+\providecommand\ltfilehookversion{v1.0g}
+\providecommand\ltfilehookdate{2021/02/08}
 %    \end{macrocode}
 %
 %<*driver>
@@ -55,6 +55,10 @@
   }
 \ExplSyntaxOff
 
+\providecommand\InternalDetectionOff{}
+\providecommand\InternalDetectionOn{}
+
+
 \usepackage{structuredlog}  % for demonstration
 
 \EnableCrossrefs
@@ -622,6 +626,7 @@
 %    When rolling forward the following expl3 functions may not be defined.
 %    If we roll back the code does nothing.
 % \changes{v1.0d}{2020/11/24}{Support for roll forward (gh/434)}
+% \InternalDetectionOff
 %    \begin{macrocode}
 %<latexrelease>\IncludeInRelease{2020/10/01}%
 %<latexrelease>                 {\file_parse_full_name_apply:nN}{Roll forward help}%
@@ -643,7 +648,8 @@
 %<latexrelease>  {
 %<latexrelease>    \tl_if_empty:nTF {#3}
 %<latexrelease>      { \__file_parse_full_name_base:nw { } #2 . \s__file_stop {#1} }
-%<latexrelease>      { \__file_parse_full_name_area:nw { #1 / #2 } #3 \s__file_stop }
+%<latexrelease>      { \__file_parse_full_name_area:nw { #1 / #2 }
+%<latexrelease>                                        #3 \s__file_stop }
 %<latexrelease>  }
 %<latexrelease>\cs_new:Npn \__file_parse_full_name_base:nw #1 #2 . #3 \s__file_stop
 %<latexrelease>  {
@@ -657,7 +663,8 @@
 %<latexrelease>          }
 %<latexrelease>          { \__file_parse_full_name_tidy:nnnN {#1} { .#2 } }
 %<latexrelease>      }
-%<latexrelease>      { \__file_parse_full_name_base:nw { #1 . #2 } #3 \s__file_stop }
+%<latexrelease>      { \__file_parse_full_name_base:nw { #1 . #2 }
+%<latexrelease>                                        #3 \s__file_stop }
 %<latexrelease>  }
 %<latexrelease>\cs_new:Npn \__file_parse_full_name_tidy:nnnN #1 #2 #3 #4
 %<latexrelease>  {
@@ -675,6 +682,7 @@
 %<latexrelease>\EndIncludeInRelease
 %<*2ekernel>
 %    \end{macrocode}
+% \InternalDetectionOn
 %
 %    \begin{macrocode}
 %<@@=>
@@ -847,6 +855,17 @@
 %<latexrelease>\long\def \InputIfFileExists#1#2{%
 %<latexrelease>  \IfFileExists{#1}%
 %<latexrelease>    {#2\@addtofilelist{#1}\@@input \@filef@und}}
+%    \end{macrocode}
+%
+%    Also undo the internal command as some packages unfortunately test
+%    for their existence instead of using \cs{IfFormatAtLeastTF}.
+% \changes{v1.0g}{2021/02/08}{Undo the internal for robust
+%                 \cs{InputIfFileExists} in rollback (gh/494)}
+%    \begin{macrocode}
+%<latexrelease>\expandafter\let\csname InputIfFileExists \endcsname\@undefined
+%    \end{macrocode}
+%
+%    \begin{macrocode}
 %<latexrelease>\let\@input@file@exists@with@hooks\@undefined
 %<latexrelease>\let\unqu@tefilef@und\@undefined
 %<latexrelease>\EndIncludeInRelease
@@ -897,7 +916,8 @@
           @file-subst@
           \@@_subst_file_normalize:Nn \use_ii_iii:nnn {#1}
         }
-        { \@@_subst_file_normalize:Nn \@@_file_name_compose:nnn {#2} }
+        { \@@_subst_file_normalize:Nn \@@_file_name_compose:nnn
+                                      {#2} }
     \group_end:
   }
 \cs_new_protected:Npn \@@_subst_remove:n #1
@@ -990,6 +1010,7 @@
 % \subsection{Selecting a file (\cs{set@curr@file})}
 %
 % \begin{macro}{\set@curr@file,\@curr@file,\@curr@file@reqd}
+%  \changes{v1.0f}{2021/01/31}{set \cs{protect} to \cs{string} gh/481}
 %   Now we hook into \cs{set@curr@file} to resolve a possible file
 %   substitution, and add \cs{@expl@@@filehook@set@curr@file@@nNN}
 %   at the end, after \cs{@curr@file} is set.
@@ -1013,11 +1034,12 @@
 %    \begin{macrocode}
 %</2ekernel>
 %<*2ekernel|latexrelease>
-%<latexrelease>\IncludeInRelease{2020/10/01}%
+%<latexrelease>\IncludeInRelease{2021/05/01}%
 %<latexrelease>          {\set@curr@file}{Setting current file name}%
 \def\set@curr@file#1{%
   \begingroup
     \escapechar\m@ne
+    \let\protect\string
     \expandafter\def\csname\expandafter\endcsname
       \expandafter{\csname\endcsname}%
 %    \end{macrocode}
@@ -1055,6 +1077,28 @@
 %    \end{macrocode}
 %    
 %    \begin{macrocode}
+%<latexrelease>\IncludeInRelease{2020/10/01}%
+%<latexrelease>\def\set@curr@file#1{%
+%<latexrelease>  \begingroup
+%<latexrelease>    \escapechar\m@ne
+%<latexrelease>    \expandafter\def\csname\expandafter\endcsname
+%<latexrelease>      \expandafter{\csname\endcsname}%
+%<latexrelease>    \@expl@@@filehook@if@no@extension@@nTF{#1}%
+%<latexrelease>      {\@tempswatrue}{\@tempswafalse}%
+%<latexrelease>    \@kernel@make@file@csname\@curr@file
+%<latexrelease>      \@expl@@@filehook@resolve@file@subst@@w {#1}%
+%<latexrelease>    \@expl@@@filehook@if@file@replaced@@TF
+%<latexrelease>      {\@kernel@make@file@csname\@curr@file@reqd
+%<latexrelease>         \@expl@@@filehook@normalize@file@name@@w{#1}%
+%<latexrelease>       \if@tempswa \@expl@@@filehook@drop@extension@@N\@curr@file@reqd \fi}%
+%<latexrelease>      {\if@tempswa \@expl@@@filehook@drop@extension@@N\@curr@file \fi
+%<latexrelease>       \global\let\@curr@file@reqd\@curr@file}%
+%<latexrelease>    \@expl@@@filehook@clear@replacement@flag@@
+%<latexrelease>  \endgroup}
+%<latexrelease>\EndIncludeInRelease
+%    \end{macrocode}
+%    
+%    \begin{macrocode}
 %<latexrelease>\IncludeInRelease{2019/10/01}%
 %<latexrelease>          {\set@curr@file}{Setting current file name}%
 %<latexrelease>\def\set@curr@file#1{%
@@ -1106,7 +1150,8 @@
   \expandafter\ifx\csname\endcsname#1%
     .tex\else\string#1\fi}
 %    \end{macrocode}
-%    
+%
+%   \begin{sloppypar}
 %   Then we call \cs{@expl@@@filehook@set@curr@file@@nNN} once for
 %   \cs{@curr@file} to set \cs[no-index]{CurrentFile(Path)Used} and once for
 %   \cs{@curr@file@reqd} to set \cs[no-index]{CurrentFile(Path)}.
@@ -1116,6 +1161,7 @@
 %   \cs{@curr@file} and \cs{@curr@file@reqd} differ.  This macro is
 %   issued separate from \cs{set@curr@file} because it changes
 %   \cs{CurrentFile}, and side-effects would quickly get out of control.
+%   \end{sloppypar}
 %    \begin{macrocode}
 \def\@filehook@set@CurrentFile{%
   \@expl@@@filehook@set@curr@file@@nNN{\@curr@file}%
@@ -1185,7 +1231,7 @@
 %</2ekernel>
 %<*2ekernel|latexrelease>
 %<latexrelease>\IncludeInRelease{2020/10/01}%
-%<latexrelease>          {\@@_resolve_file_subst:w}{Replace files detect loops}%
+%<latexrelease>     {\@@_resolve_file_subst:w}{Replace files detect loops}%
 \ExplSyntaxOn
 \cs_new:Npn \@@_resolve_file_subst:w #1 \@nil
   { \@@_file_parse_full_name:nN {#1} \@@_file_subst_begin:nnn }
@@ -1284,7 +1330,7 @@
 %</2ekernel>
 %<*2ekernel|latexrelease>
 %<latexrelease>\IncludeInRelease{2020/10/01}%
-%<latexrelease>         {\@@_file_subst_tortoise_hare:nn}{Tortoise and Hare}%
+%<latexrelease>  {\@@_file_subst_tortoise_hare:nn}{Tortoise and Hare}%
 \ExplSyntaxOn
 \cs_new:Npn \@@_file_subst_tortoise_hare:nn #1 #2 #3
   {
@@ -1437,7 +1483,7 @@
 %    \begin{macrocode}
 %<@@=>
 %    \end{macrocode}
-% 
+%  \InternalDetectionOff
 %    \begin{macrocode}
 %</2ekernel>
 %<*2ekernel|latexrelease>
@@ -1495,6 +1541,7 @@
 \cs_new_eq:NN \@expl@@@filehook@file@pop@assign@@nnnn
               \__filehook_file_pop_assign:nnnn
 %    \end{macrocode}
+%  \InternalDetectionOn
 %    
 %
 %    \begin{macrocode}
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfiles.dtx b/Master/texmf-dist/source/latex-dev/base/ltfiles.dtx
index f91dfe32aaf..b27f9105873 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfiles.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfiles.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -32,7 +32,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltfiles.dtx}
-             [2020/12/04 v1.2j LaTeX Kernel (File Handling)]
+             [2021/01/15 v1.2j LaTeX Kernel (File Handling)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltfiles.dtx}
@@ -49,6 +49,9 @@
 
 \providecommand\pkg[1]{\texttt{#1}}
 
+\providecommand\InternalDetectionOff{}
+\providecommand\InternalDetectionOn{}
+
 \begin{document}
  \MaintainedByLaTeXTeam{latex}
  \maketitle
@@ -458,12 +461,14 @@
 %    applied several times with harmful effects. We therefore
 %    explicitly drop it at this point. the coding is somewhat obscure
 %    due to the name of the macro which requires constructing.
+% \InternalDetectionOff
 %    \begin{macrocode}
 \edef \@kernel@after@begindocument@before {%
   \let\expandafter\noexpand\csname
        __hook env/document/begin\endcsname
   \noexpand\@empty}
 %    \end{macrocode}
+% \InternalDetectionOn
 %
 %    \begin{macrocode}
 \let \@kernel@before@begindocument \@empty
@@ -996,10 +1001,11 @@
 %   A side effect of the new code is that we will see quotes around
 %   file name displays where there haven't been any before.
 %
-%   For compatibility with existing code using |{abc}.tex| or |{one.two}.png|
-%   an initial brace group is discarded before expansion and |\string| is applied
-%   The content of the brace group is discarded. This means that a leading space
-%   will be lost unless protected (by |{ }| or |" "| or |\space|) but filenames
+%   For compatibility with existing code using |{abc}.tex| or
+%   |{one.two}.png|, an initial brace group is discarded before
+%   expansion and |\string| is applied.  The content of the brace
+%   group is discarded. This means that a leading space will be lost
+%   unless protected (by |{ }| or |" "| or |\space|) but filenames
 %   with a space are hopefully rare.
 %
 %  \changes{v1.2a}{2019/07/01}{Support UTF-8}
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfinal.dtx b/Master/texmf-dist/source/latex-dev/base/ltfinal.dtx
index ee45ea5588f..d6fa6e8a7bf 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfinal.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfinal.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -33,7 +33,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltfinal.dtx}
-             [2021/01/06 v2.2l LaTeX Kernel (Final Settings)]
+             [2021/02/25 v2.2m LaTeX Kernel (Final Settings)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltfinal.dtx}
@@ -525,12 +525,13 @@
 %</2ekernel>
 %<*2ekernel|latexrelease>
 %<latexrelease>\IncludeInRelease{2017/04/15}%
-%<latexrelease>                 {\document@default@language}{Save language for hyphenation}%
+%<latexrelease>       {\document@default@language}{Save language for hyphenation}%
 \let\document@default@language\m@ne
 %</2ekernel|latexrelease>
 %<latexrelease>\EndIncludeInRelease
 %<latexrelease>\IncludeInRelease{0000/00/00}%
-%<latexrelease>                 {\document@default@language}{Save language for hyphenation}%
+%<latexrelease>       {\document@default@language}{Save language for hyphenation}%
+%
 %<latexrelease>\let\document@default@language\@undefined
 %<latexrelease>\EndIncludeInRelease
 %<*2ekernel>
@@ -565,6 +566,52 @@
 \fi
 %    \end{macrocode}
 %
+%   For pdf\TeX\ preload and enable automatic glyph to Unicode mapping
+%   for more reliable copy and paste support.
+%   \changes{v2.2l}{2021/01/21}{Load glyphtounicode.tex for pdf\TeX}
+%   \changes{v2.2m}{2021/02/25}{Improve speed of ToUnicode everyjob loading code}
+%
+%    \begin{macrocode}
+%</2ekernel>
+%<*2ekernel|latexrelease>
+%<latexrelease>\IncludeInRelease{2021/05/01}%
+%<latexrelease>                 {\pdfgentounicode}{Preload glyphtounicode}%
+\ifx \pdfgentounicode \@undefined \else
+%<*2ekernel>
+  \ifnum 0=0%
+    \ifdefined\pdftexversion
+% \pdftexversion<140 does not have \pdfgentounicode, so we only check higher values
+      \ifnum \pdftexversion=140 \ifnum\pdftexrevision<22 1\fi\fi
+    \fi
+    \relax
+%</2ekernel>
+    \input glyphtounicode
+%<*2ekernel>
+  \else
+    \begingroup
+      \everyeof{\noexpand}\endlinechar-1
+      \edef\x{\endgroup
+        \everyjob{\the\everyjob\@@input glyphtounicode }%
+    }\x
+  \fi
+%</2ekernel>
+  \pdfgentounicode=1
+\fi
+%</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%    \end{macrocode}
+%   When rolling back we can't unload the glyphtounicode mappings, but we
+%   can reset |\pdfgentounicode| to ensure that they aren't used.
+%    \begin{macrocode}
+%<latexrelease>\IncludeInRelease{0000/00/00}%
+%<latexrelease>                 {\pdfgentounicode}{Preload glyphtounicode}%
+%<latexrelease>\ifx \pdfgentounicode \@undefined \else
+%<latexrelease>  \pdfgentounicode=0
+%<latexrelease>\fi
+%<latexrelease>\EndIncludeInRelease
+%<*2ekernel>
+%    \end{macrocode}
+%
 % \subsection{Input encoding}
 %
 % \changes{v2.1a}{2018/03/25}{default to UTF-8}
@@ -1147,6 +1194,7 @@
 %         {Load first aid file if existing}
 %    \begin{macrocode}
 \@input{latex2e-first-aid-for-external-files.ltx}
+\@input{ltpara.ltx}
 %    \end{macrocode}
 %
 %
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfloat.dtx b/Master/texmf-dist/source/latex-dev/base/ltfloat.dtx
index 1c8f844bc37..f2324118a04 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfloat.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfloat.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -31,7 +31,7 @@
 %
 %<*driver>
 % \fi
-\ProvidesFile{ltfloat.dtx}[2020/12/05 v1.2d LaTeX Kernel (Floats)]
+\ProvidesFile{ltfloat.dtx}[2021/02/10 v1.2f LaTeX Kernel (Floats)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltfloat.dtx}
@@ -1004,7 +1004,12 @@
 % \changes{v1.1m}{1995/05/25}{(CAR) Resettings moved to hook}
 % \changes{v1.1n}{1996/07/26}{remove unnecessary \cs{global} before
 %                 \cs{@minipage...}}
+% \changes{v1.2e}{2021/02/03}{Explicitly end with \cs{par} (gh/489)}
 %    \begin{macrocode}
+%</2ekernel>
+%<*2ekernel|latexrelease>
+%<latexrelease>\IncludeInRelease{2021/05/01}%
+%<latexrelease>                 {\@savemarbox}{Explicit par for marginpar}%
 \long\def \@savemarbox #1#2{%
   \global\setbox #1%
     \color@vbox
@@ -1012,12 +1017,35 @@
         \hsize\marginparwidth
         \@parboxrestore
         \@marginparreset
-        #2%
+        #2\par
         \@minipagefalse
         \outer@nobreak
         }%
     \color@endbox
 }
+%</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+%<latexrelease>\IncludeInRelease{0000/00/00}%
+%<latexrelease>                 {\@savemarbox}{Explicit par for marginpar}%
+%<latexrelease>
+%<latexrelease>\long\def \@savemarbox #1#2{%
+%<latexrelease>  \global\setbox #1%
+%<latexrelease>    \color@vbox
+%<latexrelease>      \vtop{%
+%<latexrelease>        \hsize\marginparwidth
+%<latexrelease>        \@parboxrestore
+%<latexrelease>        \@marginparreset
+%<latexrelease>        #2%
+%<latexrelease>        \@minipagefalse
+%<latexrelease>        \outer@nobreak
+%<latexrelease>        }%
+%<latexrelease>    \color@endbox
+%<latexrelease>}
+%<latexrelease>\EndIncludeInRelease
+%<*2ekernel>
 %    \end{macrocode}
 % \end{macro}
 %
@@ -1480,7 +1508,13 @@
 %         {Removed \cs{normalcolor} (again)}
 % \changes{v1.1t}{1997/11/19}
 %         {Missing percent, again}
+% \changes{v1.2e}{2021/02/10}{Explicitly run \cs{par} at the end of footnote text
+%      in preparation for paragraph hooks}
 %    \begin{macrocode}
+%</2ekernel>
+%<*2ekernel|latexrelease>
+%<latexrelease>\IncludeInRelease{2021/05/01}%
+%<latexrelease>                 {\@footnotetext}{footnotetext tagging}%
 \long\def\@footnotetext#1{\insert\footins{%
     \reset@font\footnotesize
     \interlinepenalty\interfootnotelinepenalty
@@ -1493,7 +1527,32 @@
     \color@begingroup
       \@makefntext{%
         \rule\z@\footnotesep\ignorespaces#1\@finalstrut\strutbox}%
+    \par
     \color@endgroup}}%
+%</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+%<latexrelease>\IncludeInRelease{0000/00/00}%
+%<latexrelease>                 {\@footnotetext}{footnotetext tagging}%
+%<latexrelease>
+%<latexrelease>\long\def\@footnotetext#1{\insert\footins{%
+%<latexrelease>    \reset@font\footnotesize
+%<latexrelease>    \interlinepenalty\interfootnotelinepenalty
+%<latexrelease>    \splittopskip\footnotesep
+%<latexrelease>    \splitmaxdepth \dp\strutbox \floatingpenalty \@MM
+%<latexrelease>    \hsize\columnwidth \@parboxrestore
+%<latexrelease>    \protected@edef\@currentlabel{%
+%<latexrelease>       \csname p@footnote\endcsname\@thefnmark
+%<latexrelease>    }%
+%<latexrelease>    \color@begingroup
+%<latexrelease>      \@makefntext{%
+%<latexrelease>        \rule\z@\footnotesep\ignorespaces#1\@finalstrut\strutbox}%
+%<latexrelease>    \color@endgroup}}%
+%<latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%<*2ekernel>
 %    \end{macrocode}
 % \end{macro}
 %
@@ -1558,10 +1617,49 @@
 %    \begin{macrocode}
 \def\@mpfn{footnote}
 \def\thempfn{\thefootnote}
-%</2ekernel>
 %    \end{macrocode}
+%
 % \end{macro}
 % \end{macro}
 %
+%
+%
+%
+%  \begin{macro}{\footref}
+%    This command generates a footnote mark. The value is produced by
+%    referencing a \cs{label} placed into a \cs{footnote} elsewhere
+%    (can be one in the main galley or in a minipage).
+% \changes{v1.2f}{2021/02/16}{\cs{footref} added}
+%    \begin{macrocode}
+%</2ekernel>
+%<*2ekernel|latexrelease>
+%<latexrelease>\IncludeInRelease{2021/05/01}%
+%<latexrelease>                 {\footref}{Add footref}%
+\def\footref#1{%
+  \begingroup
+    \unrestored@protected@xdef\@thefnmark{\ref{#1}}%
+  \endgroup
+  \@footnotemark
+}
+%</2ekernel|latexrelease>
+%<latexrelease>\EndIncludeInRelease
+%    \end{macrocode}
+%    We don't remove it when rolling back.
+%    \begin{macrocode}
+%%<latexrelease>\IncludeInRelease{0000/00/00}%
+%%<latexrelease>                 {\footref}{Add footref}%
+%%<latexrelease>
+%%<latexrelease>\let\footref\@undefined
+%%<latexrelease>
+%%<latexrelease>\EndIncludeInRelease
+%<*2ekernel>
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%    \begin{macrocode}
+%</2ekernel>
+%    \end{macrocode}
+%
 % \Finale
 %
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfntcmd.dtx b/Master/texmf-dist/source/latex-dev/base/ltfntcmd.dtx
index 8d587a848a5..5f70053a688 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfntcmd.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfntcmd.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfssaxes.dtx b/Master/texmf-dist/source/latex-dev/base/ltfssaxes.dtx
index 4e3b4d983cc..e0c07874556 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfssaxes.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfssaxes.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 2019-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -35,7 +35,7 @@
 %
 %
 \ProvidesFile{ltfssaxes.dtx}
-             [2020/12/22 v1.0h LaTeX Kernel (NFSS Axes handing)]
+             [2021/01/15 v1.0h LaTeX Kernel (NFSS Axes handing)]
 % \iffalse
 \documentclass{ltxdoc}
 \begin{document}
@@ -764,8 +764,10 @@
 %<latexrelease>\IncludeInRelease{2020/02/02}%
 %<latexrelease>                 {\fontseries}{delay fontseries update}%
 %<latexrelease>
-%<latexrelease>\DeclareRobustCommand\fontseries[1]{\@forced@seriesfalse\merge@font@series{#1}}
-%<latexrelease>\DeclareRobustCommand\fontseriesforce[1]{\@forced@seriestrue\edef\f@series{#1}}
+%<latexrelease>\DeclareRobustCommand\fontseries[1]{\@forced@seriesfalse
+%<latexrelease>                                    \merge@font@series{#1}}
+%<latexrelease>\DeclareRobustCommand\fontseriesforce[1]{\@forced@seriestrue
+%<latexrelease>                                         \edef\f@series{#1}}
 %<latexrelease>\let\delayed@f@adjustment\@undefined
 %<latexrelease>
 %    \end{macrocode}
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfssbas.dtx b/Master/texmf-dist/source/latex-dev/base/ltfssbas.dtx
index d2dde745d4c..6d575fc9d0b 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfssbas.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfssbas.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfsscmp.dtx b/Master/texmf-dist/source/latex-dev/base/ltfsscmp.dtx
index 29580b8d5e5..03be855127d 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfsscmp.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfsscmp.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfssdcl.dtx b/Master/texmf-dist/source/latex-dev/base/ltfssdcl.dtx
index 725d0e39fcc..9710d543829 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfssdcl.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfssdcl.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -36,7 +36,7 @@
 %
 %
 \ProvidesFile{ltfssdcl.dtx}
-            [2020/12/05 v3.0v LaTeX Kernel (NFSS Declarative Interface)]
+            [2021/02/15 v3.0w LaTeX Kernel (NFSS Declarative Interface)]
 % \iffalse
 \documentclass{ltxdoc}
 \begin{document}
@@ -490,7 +490,11 @@
                    in version \math@version}%
         \@eha
   \fi
- \else \expandafter\non@alpherr\fi
+%    \end{macrocode}
+% extra \cs{expandafter} to remove the \cs{expandafter} added below
+% \changes{v3.0w}{2021/02/115}{fix for (gh/501)}
+%    \begin{macrocode}
+ \else \expandafter\expandafter\expandafter\non@alpherr\fi
 %    \end{macrocode}
 %    If the legacy interface is used, e.g., \verb=$\sf -1$= the math
 %    alphabet \verb=#1= does not take an argument so we better do not
@@ -1526,7 +1530,7 @@
 \def\set@mathdelimiter#1#2#3#4#5#6{%
 %    \end{macrocode}
 %    We use \cs{protected} not \cs{MakeRobust} so that
-%    \verb=\bigl\lfoor= etc.\ works inside \cs{protected@edef}.
+%    \verb=\bigl\lfoor= etc.\ works inside the argument of \cs{protected@edef}.
 % \changes{v3.0s}{2019/08/27}{Make math delimiters robust}
 % \changes{v3.0t}{2020/01/20}{fix for gh/251}
 %    \begin{macrocode}
@@ -1733,7 +1737,7 @@
       \relax
 %    \end{macrocode}
 %    If it is undefined, fine otherwise check if it is a math alphabet
-%    defined via |\DeclareSymbolFontAlphabet|:
+%    defined via \\ |\DeclareSymbolFontAlphabet|:
 %    \begin{macrocode}
       \else
         \edef\reserved@a{%
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfssini.dtx b/Master/texmf-dist/source/latex-dev/base/ltfssini.dtx
index a92321bf5d7..361adac9c36 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfssini.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfssini.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -36,7 +36,7 @@
 %
 %
 \ProvidesFile{ltfssini.dtx}
-             [2020/12/06 v3.2f LaTeX Kernel (NFSS Initialisation)]
+             [2021/01/15 v3.2f LaTeX Kernel (NFSS Initialisation)]
 % \iffalse
 \documentclass{ltxdoc}
 \begin{document}
@@ -448,7 +448,7 @@
 %    \item \cs{bfseries} is called  for a family using \texttt{bx}
 %       (e.g., CMR) 
 %    \item Switch to a font family that is none of the meta
-%       families, e.g., via \verb=\fontfamily{ptm}\selectfont=
+%       families, e.g., via \verb=\fontfamily{ptm}\allowbreak\verb=\selectfont=
 %    \item Then none of the real meta families, match but the final
 %      \verb=\@elt{??}= will.
 %    \item Therefore if the current series is \cs{mddefault} or
@@ -1307,8 +1307,9 @@
 }
 %    \end{macrocode}
 %  \end{macro}
-
-
+%
+%
+%
 %  \begin{macro}{\if@font@series@context}
 %    The boolean to signal if we found the requested font series context.
 %    \begin{macrocode}
@@ -1334,9 +1335,11 @@
 %<latexrelease>\EndIncludeInRelease
 %<*2ekernel>
 %    \end{macrocode}
-
-
-
+%
+%
+%
+%
+%
 %
 % \section{Supporting nested emphasis}
 %
@@ -1401,9 +1404,9 @@
 \let\emfontdeclare@clist\@empty
 %    \end{macrocode}
 %  \end{macro}
-
-
-
+%
+%
+%
 %  \begin{macro}{\emrest}
 %    Reset the font to upright and upper/lower case. With the default rules
 %    using \cs{shapedefault} does that for us but to be on the safe side we
@@ -1412,12 +1415,13 @@
 \DeclareRobustCommand\emreset{\upshape\ulcshape}
 %    \end{macrocode}
 %  \end{macro}
-
-
-
+%
+%
+%
 %  \begin{macro}{\em}
-%    The new definition for \cs{em} (and implicitly \cs{emph} is like
-%    it was before if \cs{emfontdeclare@clist} is empty.
+%
+%    The new definition for \cs{em} (and implicitly \cs{emph}) is the
+%    same as before as long as \cs{emfontdeclare@clist} is empty.
 %    \begin{macrocode}
 \DeclareRobustCommand\em{%
   \@nomath\em
diff --git a/Master/texmf-dist/source/latex-dev/base/ltfsstrc.dtx b/Master/texmf-dist/source/latex-dev/base/ltfsstrc.dtx
index bd0f6fabd21..961abafc8a3 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltfsstrc.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltfsstrc.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -30,7 +30,7 @@
 % \iffalse
 %%% From File: ltfsstrc.dtx
 %% Copyright (C) 1989-97 by Frank Mittelbach and Rainer Sch\"opf.
-%% Copyright (C) 1994-97 by LaTeX3 project. All rights reserved.
+%% Copyright (C) 1994-97 by LaTeX Project. All rights reserved.
 %
 %<package>\NeedsTeXFormat{LaTeX2e}[2021/05/01]
 %<package>\ProvidesPackage{tracefnt}
diff --git a/Master/texmf-dist/source/latex-dev/base/lthooks.dtx b/Master/texmf-dist/source/latex-dev/base/lthooks.dtx
index 404938d203a..803914b4a74 100644
--- a/Master/texmf-dist/source/latex-dev/base/lthooks.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/lthooks.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
-%%
-%% File: lthooks.dtx (C) Copyright 2020,2021 Frank Mittelbach,
-%%                                      Phelype Oleinik & LaTeX Team
+%
+% Copyright (C)  2020-2021
+%       Frank Mittelbach, Phelype Oleinik & LaTeX Team
 %
 % This file is part of the LaTeX base system.
 % -------------------------------------------
@@ -32,7 +32,7 @@
 %
 %    \begin{macrocode}
 \def\lthooksversion{v1.0h}
-\def\lthooksdate{2021/01/07}
+\def\lthooksdate{2021/01/15}
 %    \end{macrocode}
 %
 %<*driver>
@@ -54,6 +54,9 @@
   }
 \ExplSyntaxOff
 
+\providecommand\InternalDetectionOff{}
+\providecommand\InternalDetectionOn{}
+
 \EnableCrossrefs
 \CodelineIndex
 \begin{document}
@@ -1336,14 +1339,8 @@
 %   Like \cs{AtBeginDocument} but for the \hook{enddocument} hook.
 % \end{function}
 %
-%
-%
-% \begin{function}{\AtBeginDvi}
-%   \begin{syntax}
-%     \cs{AtBeginDvi} \oarg{label} \Arg{code}
-%   \end{syntax}
-%   This hook is discussed in conjunction with the shipout hooks.
-% \end{function}
+%    There is also \cs{AtBeginDvi}  which is discussed in conjunction
+%    with the shipout hooks.
 %
 %    \bigskip
 %
@@ -1772,9 +1769,11 @@
 %
 % \begin{macro}[EXP]{\@@_str_compare:nn}
 %   Private copy of \cs{__str_if_eq:nn}
+% \InternalDetectionOff  
 %    \begin{macrocode}
 \cs_new_eq:NN \@@_str_compare:nn \__str_if_eq:nn
 %    \end{macrocode}
+% \InternalDetectionOn
 % \end{macro}
 %
 %  \subsection{Declarations}
@@ -2898,9 +2897,11 @@
 %   together in hook |#1|.
 %    \begin{macrocode}
 \cs_new_protected:cpn { @@_rule_incompatible-error_gset:nnn } #1#2#3
-  { \@@_tl_gset:cn { g_@@_#1_rule_ \@@_label_pair:nn {#2} {#3} _tl } { xE } }
+  { \@@_tl_gset:cn { g_@@_#1_rule_ \@@_label_pair:nn {#2} {#3} _tl }
+                   { xE } }
 \cs_new_protected:cpn { @@_rule_incompatible-warning_gset:nnn } #1#2#3
-  { \@@_tl_gset:cn { g_@@_#1_rule_ \@@_label_pair:nn {#2} {#3} _tl } { xW } }
+  { \@@_tl_gset:cn { g_@@_#1_rule_ \@@_label_pair:nn {#2} {#3} _tl }
+                   { xW } }
 %    \end{macrocode}
 %  \end{macro}
 %
@@ -4449,6 +4450,7 @@
 %  \begin{macro}{\@expl@@@initialize@all@@,
 %                \@expl@@@hook@curr@name@pop@@}
 %
+% \InternalDetectionOff
 %    \begin{macrocode}
 \cs_new_eq:NN \@expl@@@initialize@all@@
               \__hook_initialize_all:
@@ -4458,6 +4460,7 @@
 \cs_new_eq:NN \@expl@@@hook@curr@name@pop@@
               \__hook_curr_name_pop:
 %    \end{macrocode}
+% \InternalDetectionOn
 %  \end{macro}
 %
 %    
diff --git a/Master/texmf-dist/source/latex-dev/base/lthyphen.dtx b/Master/texmf-dist/source/latex-dev/base/lthyphen.dtx
index f8321719c72..9244db06423 100644
--- a/Master/texmf-dist/source/latex-dev/base/lthyphen.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/lthyphen.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -40,7 +40,7 @@
 %\iffalse        This is a META comment
 %
 % File `lthyphen.dtx'.
-% Copyright (C) 1994-94 LaTeX3 project, Frank Mittelbach and
+% Copyright (C) 1994-94 LaTeX Project, Frank Mittelbach and
 % Rainer Sch\"opf, all rights reserved.
 %
 %\fi
diff --git a/Master/texmf-dist/source/latex-dev/base/ltidxglo.dtx b/Master/texmf-dist/source/latex-dev/base/ltidxglo.dtx
index f435fea4d04..75a80cd4390 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltidxglo.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltidxglo.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltlength.dtx b/Master/texmf-dist/source/latex-dev/base/ltlength.dtx
index 388aac78d7e..1be147547ec 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltlength.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltlength.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltlists.dtx b/Master/texmf-dist/source/latex-dev/base/ltlists.dtx
index 087b418847f..fecb3125880 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltlists.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltlists.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltlogos.dtx b/Master/texmf-dist/source/latex-dev/base/ltlogos.dtx
index 6fd7b35c928..132eaf636f7 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltlogos.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltlogos.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltluatex.dtx b/Master/texmf-dist/source/latex-dev/base/ltluatex.dtx
index 957a71d8488..e3fa9f93437 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltluatex.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltluatex.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 2015-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -28,7 +28,7 @@
 \ProvidesFile{ltluatex.dtx}
 %</driver>
 %<*tex>
-[2020/12/06 v1.1s
+[2021/01/15 v1.1s
 %</tex>
 %<plain>  LuaTeX support for plain TeX (core)
 %<*tex>
@@ -38,6 +38,10 @@
 %</tex>
 %<*driver>
 \documentclass{ltxdoc}
+
+\providecommand\InternalDetectionOff{}
+\providecommand\InternalDetectionOn{}
+
 \GetFileInfo{ltluatex.dtx}
 \begin{document}
 \title{\filename\\(Lua\TeX{}-specific support)}
@@ -204,6 +208,7 @@
 % The number is returned and also \meta{name} argument is added to the
 % |lua.name| array at that index.
 %
+% \begin{sloppypar}
 % \noindent
 % \DescribeMacro{new_luafunction}
 % |luatexbase.new_luafunction(|\meta{functionname}|)|\\
@@ -211,6 +216,7 @@
 % with |\luafunction|, |\lateluafunction|, and |\luadef|,
 % indexed from~$1$. The optional \meta{functionname} argument
 % is just used for logging.
+% \end{sloppypar}
 %
 % These functions all require access to a named \TeX{} count register
 % to manage their allocations. The standard names are those defined
@@ -1116,6 +1122,7 @@ luatexbase.registernumber = registernumber
 % \changes{v1.1c}{2017/02/18}{Parameterize count used in tracking}
 %   As attributes are used for Lua manipulations its useful to be able
 %   to assign from this end.
+% \InternalDetectionOff
 %    \begin{macrocode}
 local attributes=setmetatable(
 {},
@@ -1143,6 +1150,7 @@ local function new_attribute(name)
 end
 luatexbase.new_attribute = new_attribute
 %    \end{macrocode}
+% \InternalDetectionOn
 % \end{macro}
 %
 % \subsection{Custom whatsit allocation}
diff --git a/Master/texmf-dist/source/latex-dev/base/ltmath.dtx b/Master/texmf-dist/source/latex-dev/base/ltmath.dtx
index 58ca26b4a5f..ca90e1980d2 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltmath.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltmath.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltmiscen.dtx b/Master/texmf-dist/source/latex-dev/base/ltmiscen.dtx
index c7254ad3532..939bd51a2da 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltmiscen.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltmiscen.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -32,7 +32,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltmiscen.dtx}
-             [2020/12/18 v1.1x LaTeX Kernel (Misc. Environments)]
+             [2021/02/08 v1.1y LaTeX Kernel (Misc. Environments)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltmiscen.dtx}
@@ -868,6 +868,15 @@
 %<latexrelease>  \expandafter\endgroup\if@endpe\@doendpe\fi
 %<latexrelease>  \if@ignore\@ignorefalse\ignorespaces\fi}
 %<latexrelease>
+%    \end{macrocode}
+%    Also undo the internal commands as some packages unfortunately test
+%    for their existence instead of using \cs{IfFormatAtLeastTF}.
+% \changes{v1.1y}{2021/02/08}{Undo the internals for robust \cs{begin}
+%    and \cs{end} in rollback (gh/494)}
+%    \begin{macrocode}
+%<latexrelease>\expandafter\let\csname begin \endcsname\@undefined
+%<latexrelease>\expandafter\let\csname end \endcsname\@undefined
+%<latexrelease>
 %<latexrelease>\EndIncludeInRelease
 %<*2ekernel>
 %    \end{macrocode}
diff --git a/Master/texmf-dist/source/latex-dev/base/ltoutenc.dtx b/Master/texmf-dist/source/latex-dev/base/ltoutenc.dtx
index 4eea0ad41ec..73146428c0d 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltoutenc.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltoutenc.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -37,14 +37,14 @@
 %<TS1>\ProvidesFile{ts1enc.def}[2001/06/05 v3.0e (jk/car/fm)
 %<TU>\ProvidesFile{tuenc.def}
 %<package>\ProvidesPackage{fontenc}
-%<OT1|T1|OMS|OML|OT4|TU|package> [2020/08/10 v2.0s
+%<OT1|T1|OMS|OML|OT4|TU|package> [2021/02/19 v2.0u
 %<OT1|T1|OMS|OML|OT4|TS1|TU>      Standard LaTeX file]
 %<package>                        Standard LaTeX package]
 %
 %<*driver>
 % \fi
 \ProvidesFile{ltoutenc.dtx}
-             [2020/12/05 v2.0s LaTeX Kernel (font encodings)]
+             [2021/02/19 v2.0u LaTeX Kernel (font encodings)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltoutenc.dtx}
@@ -1717,6 +1717,17 @@
 \DeclareTextSymbol{\textemdash}{OT1}{124}
 \DeclareTextSymbol{\textendash}{OT1}{123}
 %    \end{macrocode}
+%    
+%    The \verb=\nobreak\hskip\z@= is there to prevent a break after
+%    the hyphen but allow later breaks in the remainder of the word. 
+% \changes{v2.0u}{2021/02/19}{Add \cs{textnonbreakinghyphen}, \cs{textfiguredash}
+%      and \cs{texthorizontalbar} (gh/404)}
+%    \begin{macrocode}
+\DeclareTextCommand{\textnonbreakinghyphen}{OT1}{\mbox{-}\nobreak\hskip\z@}
+\DeclareTextCommand{\textfiguredash}       {OT1}{\textendash}
+\DeclareTextCommand{\texthorizontalbar}    {OT1}{\textemdash}
+%    \end{macrocode}
+%
 %    Using the ligatures helps with OT1 fonts that have
 %    |\textexclamdown| and |\textquestiondown| in unusual positions.
 % \changes{v1.95}{2002/06/17}{Definition of \cs{textexclamdown} changed (pr/3368)}
@@ -2045,6 +2056,19 @@
 \DeclareTextSymbol{\textdollar}{T1}{`\$}
 \DeclareTextSymbol{\textemdash}{T1}{22}
 \DeclareTextSymbol{\textendash}{T1}{21}
+%    \end{macrocode}
+%
+%    The \verb=\nobreak\hskip\z@= is there to prevent a break after
+%    the hyphen but allow later breaks in the remainder of the word. 
+% \changes{v2.0u}{2021/02/19}{Add \cs{textnonbreakinghyphen}, \cs{textfiguredash}
+%      and \cs{texthorizontalbar} (gh/404)}
+%    \begin{macrocode}
+\DeclareTextCommand{\textnonbreakinghyphen}{T1}{\mbox{-}\nobreak\hskip\z@}
+\DeclareTextCommand{\textfiguredash}       {T1}{\textendash}
+\DeclareTextCommand{\texthorizontalbar}    {T1}{\textemdash}
+%    \end{macrocode}
+%
+%    \begin{macrocode}
 \DeclareTextSymbol{\textexclamdown}{T1}{189}
 \DeclareTextSymbol{\textgreater}{T1}{`\>}
 %\DeclareTextSymbol{\texthyphenchar}{T1}{127}
@@ -2583,8 +2607,31 @@
 \DeclareTextSymbol{\textquotesingle}{TS1}{39}
 %    \end{macrocode}
 %    "28 = 40
-%    \begin{macrocode}
-\DeclareTextSymbol{\textasteriskcentered}{TS1}{42}
+%
+%    The symbol \cs{textasteriskcentered} ``\textasteriskcentered'' is
+%    supposed to be always available in \texttt{TS1} and that is
+%    important as it is used in footnote symbols. However, in a few
+%    fonts it is missing even though they are otherwise fairly
+%    complete. We therefore use a rather elaborate method and check if
+%    the slot has a glyph and if not produce a poor man's version by
+%    using a normal ``*'' slightly enlarged and somewhat lowered.
+%    The main application for this symbol is in footnote symbols and
+%    there it should produce a comparable size and show a similar placement.
+% \changes{v2.0t}{2021/02/17}{Special definition for
+%        \cs{textasteriskcentered} when missing in TS1 (gh/502)}
+%    \begin{macrocode}
+%\DeclareTextSymbol{\textasteriskcentered}{TS1}{42} % that's wanted
+\DeclareTextCommand \textasteriskcentered{TS1}{%    % and that's needed
+  \iffontchar\font 42 \char42 \else 
+   \begingroup\fontencoding{T1}%
+       \fontsize
+       {\the\dimexpr1.3\dimexpr\f@size pt\relax}%
+       {\f@baselineskip}%
+      \selectfont
+      \raisebox{-0.7ex}[\dimexpr\height-0.7ex][0pt]{*}%
+    \endgroup
+    \fi
+}
 %    \end{macrocode}
 % Note that '054 is a comma and '056 is a full stop: these make
 % numbers using oldstyle digits easier to input.
@@ -3106,8 +3153,34 @@
 \DeclareTextSymbol{\textbaht}            \UnicodeEncodingName{"0E3F}
 \DeclareTextSymbol{\SS}                  \UnicodeEncodingName{"1E9E}
 \DeclareTextSymbol{\textcompwordmark}    \UnicodeEncodingName{"200C}
+%    \end{macrocode}
+%    
+% \changes{v2.0u}{2021/02/19}{Add \cs{textnonbreakinghyphen}, \cs{textfiguredash}
+%      and \cs{texthorizontalbar} (gh/404)}
+%    \begin{macrocode}
+%\DeclareTextSymbol{\textnonbreakinghyphen} \UnicodeEncodingName{"2011}
+%\DeclareTextSymbol{\textfiguredash}        \UnicodeEncodingName{"2012}
 \DeclareTextSymbol{\textendash}          \UnicodeEncodingName{"2013}
 \DeclareTextSymbol{\textemdash}          \UnicodeEncodingName{"2014}
+%\DeclareTextSymbol{\texthorizontalbar}   \UnicodeEncodingName{"2015}
+%    \end{macrocode}
+%    Unfortunately some fonts do not implement \texttt{"2011}, \texttt{"2012} and/or
+%    \texttt{"2015} (including the \LaTeX{} default fonts for Unicode
+%    engines) so we provide some approximations if the glyph is
+%    missing, like we do for \texttt{OT1} and \texttt{T1}.
+%
+%    The \verb=\nobreak\hskip\z@= is there to prevent a break after
+%    the hyphen but allow later breaks in the remainder of the word. 
+%    \begin{macrocode}
+\DeclareTextCommand{\textnonbreakinghyphen} \UnicodeEncodingName
+     {\iffontchar\font "2011 \char "2011 \else \mbox{-}\nobreak\hskip\z@ \fi}
+\DeclareTextCommand{\textfiguredash}     \UnicodeEncodingName
+     {\iffontchar\font "2012 \char "2012 \else \char "2013 \fi}
+\DeclareTextCommand{\texthorizontalbar}     \UnicodeEncodingName
+     {\iffontchar\font "2015 \char "2015 \else \char "2014 \fi}
+%    \end{macrocode}
+%    
+%    \begin{macrocode}
 \DeclareTextSymbol{\textbardbl}          \UnicodeEncodingName{"2016}
 \DeclareTextSymbol{\textquoteleft}       \UnicodeEncodingName{"2018}
 \DeclareTextSymbol{\textquoteright}      \UnicodeEncodingName{"2019}
@@ -3159,15 +3232,17 @@
 %    \end{macrocode}
 %
 % Not all fonts have U+2217 but using U+002A requires some adjustment.
+% \changes{v2.0t}{2021/02/17}{Adjust values for
+%        \cs{textasteriskcentered} To match TS1 definition (gh/502)}
 %    \begin{macrocode}
 \DeclareTextCommand{\textasteriskcentered}\UnicodeEncodingName{%
   \iffontchar\font"2217 \char"2217 \else
     \begingroup
       \fontsize
-       {\the\dimexpr1.2\dimexpr\f@size pt\relax}%
+       {\the\dimexpr1.3\dimexpr\f@size pt\relax}%
        {\f@baselineskip}%
       \selectfont
-      \raisebox{-0.6ex}[\dimexpr\height-0.6ex][0pt]{*}%
+      \raisebox{-0.7ex}[\dimexpr\height-0.7ex][0pt]{*}%
     \endgroup
   \fi
 }
diff --git a/Master/texmf-dist/source/latex-dev/base/ltoutenc.ins b/Master/texmf-dist/source/latex-dev/base/ltoutenc.ins
index 23c27697f84..1330b5c44eb 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltoutenc.ins
+++ b/Master/texmf-dist/source/latex-dev/base/ltoutenc.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltoutput.dtx b/Master/texmf-dist/source/latex-dev/base/ltoutput.dtx
index f418459f661..69bfa1f036b 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltoutput.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltoutput.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -57,7 +57,7 @@
 % \iffalse
 % LATEX VERSION 2e
 % Copyright (C) 1992 by Leslie Lamport
-% Copyright (C) 1994-2000 by Leslie Lamport, LaTeX3 project
+% Copyright (C) 1994-2000 by Leslie Lamport, LaTeX Project
 %
 % LaTeX 2e kernel file for the output routine.
 %
diff --git a/Master/texmf-dist/source/latex-dev/base/ltpage.dtx b/Master/texmf-dist/source/latex-dev/base/ltpage.dtx
index ce6681e7e08..4504033f542 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltpage.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltpage.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltpageno.dtx b/Master/texmf-dist/source/latex-dev/base/ltpageno.dtx
index 80055c7c5d9..03d36a53d98 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltpageno.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltpageno.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltpar.dtx b/Master/texmf-dist/source/latex-dev/base/ltpar.dtx
index 169954f9ea8..f4f3d5e63fc 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltpar.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltpar.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltpara.dtx b/Master/texmf-dist/source/latex-dev/base/ltpara.dtx
new file mode 100644
index 00000000000..1a3df95a6e2
--- /dev/null
+++ b/Master/texmf-dist/source/latex-dev/base/ltpara.dtx
@@ -0,0 +1,1159 @@
+% \iffalse meta-comment
+%
+%% File: ltpara.dtx (C) Copyright 2020-2021
+%       Frank Mittelbach, LaTeX Team
+%
+% It may be distributed and/or modified under the conditions of the
+% LaTeX Project Public License (LPPL), either version 1.3c of this
+% license or (at your option) any later version.  The latest version
+% of this license is in the file
+%
+%    https://www.latex-project.org/lppl.txt
+%
+%
+%%% From File: lthooks.dtx
+%
+%    \begin{macrocode}
+\def\ltparaversion{v1.0d}
+\def\ltparadate{2021/02/18}
+%    \end{macrocode}
+%<*driver>
+\documentclass{l3doc}
+
+%\usepackage{ltpara}
+
+% Fixing footnotes in  functions and variables: this should be in l3doc!
+\newcommand\fixfootnote[2]{\footnotemark
+  \AddToHookNext{env/#1/after}{\footnotetext{#2}}}
+\AddToHook{env/function/begin}{\def\footnote{\fixfootnote{function}}}
+\AddToHook{env/variable/begin}{\def\footnote{\fixfootnote{variable}}}
+
+\EnableCrossrefs
+\CodelineIndex
+\begin{document}
+  \DocInput{ltpara.dtx}
+\end{document}
+%</driver>
+%
+% \fi
+%
+% \providecommand\hook[1]{\texttt{#1}}
+% \providecommand\env[1]{\texttt{#1}}
+%
+%
+%
+% \title{The \texttt{ltpara.dtx} code\thanks{This file has version
+%    \ltparaversion\ dated \ltparadate, \copyright\ \LaTeX\
+%    Project.}}
+% \author{Frank Mittelbach}
+%
+% \maketitle
+%
+%
+% \begin{abstract}
+%    This code defines four special kernel hooks to support paragraph
+%    tagging as well as four public hooks which can be occasionally
+%    useful.
+% \end{abstract}
+%
+% \tableofcontents
+%
+%
+% \section{Introduction}
+%
+%
+%    The building of paragraphs in the \TeX{} engine(s) has a number
+%    of peculiarities that makes it on one hand fairly flexible but on
+%    the other hand somewhat awkward to control or reliably to extend.
+%    Thus to better understand the code below we start with a brief introduction
+%    of the mechanism; for more details refer to the
+%    \TeX{}book~\cite[chap.~14]{texbook} (for the full truth you may
+%    even have to study the program code).
+%
+% \subsection{The default processing done by the engine}
+%
+%    \TeX{} automatically starts building a paragraph when it is
+%    currently in vertical mode and encounters anything that can only
+%    live in horizontal mode. Most often this is a character, but
+%    there are also many commands that can be used only in horizontal mode.
+%    If any of them is encountered, \TeX{} will immediately back up
+%    (i.e., the character or command is read later again), adds a
+%    \cs{parskip} glue to the current vertical list unless the list is
+%    empty, switches to
+%    horizontal mode, starts its special \enquote{start of paragraph
+%    processing} and only then rereads the character or command that
+%    caused the mode change.\footnote{Already not quite true: the
+%    command \cs{noindent} starts the paragraph but influences the
+%    special processing by suppressing the paragraph indentation box
+%    normally inserted by it.}
+%
+%    This \enquote{start of paragraph
+%    processing} first adds an empty box at the start of the
+%    horizontal list of width \cs{parindent} (which represents the
+%    paragraph indentation) unless the paragraph was started with
+%    \cs{noindent} in which case no such box is
+%    added\footnote{That's a bit different from placing a zero-sized
+%    box!}. It then reads and processes all tokens stored in the
+%    special engine token register \cs{everypar}. After that it reads
+%    and processes whatever has caused the paragraph to start.
+%
+%    Thus out of the box, \TeX{} offers the possibility to put some
+%    special code into \cs{everypar} to gain control at (more or less)
+%    the start of the paragraph. For example, in LaTeX{} and a number
+%    of packages,  special code like the following is sometimes used:
+%\begin{verbatim}
+%  \everypar{{\setbox\z@\lastbox}\everypar{} ...}
+%\end{verbatim}
+%    This removes the paragraph indentation box again  (that was already
+%    placed by \TeX), then resets \cs{everypar} so that it doesn't do
+%    anything on the next paragraph start and then does whatever it
+%    wants to do, e.g., in an \cs{item} of a list it will typeset the label in
+%    front of the paragraph text.
+%    However, there is only one such \cs{everypar} token register and
+%    if different packages and/or the kernel all attempt to add their
+%    own code here, coordination is very difficult if not impossible.
+%
+%    The process when the paragraph ends has different mechanisms and interfaces.
+%    A paragraph ends when the engine  primitive \cs{par} is called
+%    while \TeX{} is in unrestricted horizontal mode, i.e., is
+%    building a paragraph. At other times this primitive does nothing
+%    or generates as an error depending on the mode \TeX{} is in,
+%    e.g., the \cs{par} in
+%    \verb=\hbox{a\par b}= is ignored, but \verb=$a\par b$= would complain.
+%
+%    If this primitive ends the paragraph it does some special
+%    \enquote{end of horizontal list} processing, then calls \TeX{} paragraph
+%    builder that breaks the horizontal list into lines then these
+%    lines are added as boxes to the enclosing vertical list and
+%    \TeX{} returns to vertical mode.
+%
+%    This \cs{par} command can be given explicitly, but there are also
+%    situations in which \TeX{} is generating it on the fly. Most
+%    often this happens when \TeX\ encounters a blank line which is
+%    automatically changed to a \cs{par} command which is then
+%    executed. The other possibility is that \TeX{} encounters a
+%    command which is incompatible with horizontal processing, e.g.,
+%    \cs{vskip} (a request for adding vertical space). In such case it
+%    silently backs up, and inserts a \cs{par} in the hope that this
+%    gets it out of horizontal mode and makes the offending command
+%    acceptable.
+
+%    The important point to note here is that \TeX{} really inserts
+%    the command \cs{par} which can be redefined. Thus, it may not have
+%    its original \enquote{primitive} meaning and therefore may not end the
+%    horizontal list and call the paragraph builder. This approach
+%    offers some flexibility but also allows you  to easily produce a
+%    \TeX{} document that loops forever, for example, the simple line
+%\begin{verbatim}
+%   A \let\par\relax \vskip
+%\end{verbatim}
+%    will start a horizontal list at \texttt{A}, redefines \cs{par},
+%    then sees \cs{vskip} and inserts \cs{par} to end the
+%    paragraph. But this now only runs \cs{relax} so nothing changes
+%    and \cs{vskip} is read again, issues a \cs{par} which \ldots. In
+%    short, it takes a plain \TeX{} document with five tokens to run
+%    forever (as not even memory is consumed and therefore eventually
+%    exhausted).
+%
+%    There are no other ways than changing \cs{par} to gain control at
+%    the end of a paragraph, i.e., there is no token list like
+%    \cs{everypar} that is inserted, i.e., the only way to change the
+%    default behavior is to modify the action that \cs{par} executes
+%    with similar issues as outlined before: different processes need
+%    to ensure that they do not overwrite their modifications or
+%    worse, think that the \cs{par} in front of them is the engine
+%    primitive while in fact it has already been changed by other
+%    code.
+%
+%
+%    To make matters slightly worse there are a few places where
+%    \TeX{} handles the situation differently (most likely for speed
+%    reasons back when computers were much slower). If \TeX{} finds
+%    itself in unrestricted horizontal mode at the end of building a
+%    vertical box (or an \cs{insert}, \cs{vadjust} or at the end of
+%    executing the output routine code), it will finish the horizontal
+%    list not by issuing a \cs{par} command (which would be consistent
+%    with all other places, but by simply executing the primitive version
+%    of \cs{par} regardless of the definition that \cs{par} has at the
+%    time.
+%
+%    Thus, if you have carefully crafted a redefined \cs{par} to execute
+%    some special actions at the end of a paragraph and you write
+%    something like
+%\begin{verbatim}
+%   \vbox{Some paragraph ... text.}
+%\end{verbatim}
+%    you will find that your code has never run for the last paragraph
+%    in that box. \LaTeX{} avoids this problem, by making sure that
+%    all its boxes (such as \cs{parbox} or the \env{minipage}
+%    environment, etc.) all internally add an explicit \cs{par} at the
+%    end so that such code is run and \TeX{} finds itself in vertical
+%    mode already without the need to start up the paragraph builder
+%    internally. But, of course, this only works for boxes under direct
+%    control of the \LaTeX{} kernel, if some package uses low-level
+%    \cs{vbox}es without adding this precaution the \TeX{}
+%    optimization kicks in and no special \cs{par} code is executed.
+%
+%    And there is another optimization that is painful: if a paragraph
+%    is interrupted by a mathematical display, e.g., \verb=\[...\]= in
+%    \LaTeX{} or \verb=$$...$$= in plain \TeX{}, then \TeX{} will
+%    resume horizontal mode afterward, i.e., build a new horizontal
+%    list (without inserting an indentation box or \cs{everypar} at
+%    that point). However, if that list immediately ends with an
+%    explicit or implicit \cs{par} then \TeX{} will simply throw away
+%    this \enquote{null} paragraph and not do its usual \enquote{end
+%    of horizontal list} processing, so this special case need to be
+%    accounted for when introducing some extended processing.
+%
+%
+%
+% \section{The new mechanism implemented for \LaTeX{}}
+%
+%    To improve the situation (and also to support automatic tagging
+%    of PDF documents) we now offer public as well as private hooks at
+%    the start and end of the paragraph processing. The public hooks
+%    can be used by packages (or by the user in the preamble or
+%    within the document) and using the hook mechanisms it is possible
+%    to reorder or arrange code from different packages in a way that
+%    it can safely coexist.
+%
+%    To make that happen we have to make use of the basic
+%    functionality that is offered by \TeX{}, e.g., we install
+%    special code inside \cs{everypar} to provide hooks at the
+%    beginning and we redefine \cs{par} to do some special processing
+%    when appropriate to install hooks at the end of the paragraph.
+%
+%    In order to make this work, we have to ensure that package use of
+%    \cs{everypar} is not overwriting our code. This is done through a
+%    trick: we basically hide the real \cs{everypar} from the packages
+%    and offer them a new token register (with the same name). So if
+%    they install their own code it doesn't overwrite ours. Our code
+%    then inserts the new \cs{everypar} at the right place inside the
+%    process so that it looks as if it was the primitive
+%    \cs{everypar}.\footnote{Ideally, \cs{everypar} wouldn't be used
+%    at all by packages and instead they would simply write their code
+%    into the hooks now offered by the kernel. However, while this is
+%    the longterm goal and clearly an improvement (because then the
+%    packages do no longer need to worry about getting their code
+%    overwritten or needing to account for already existing code in
+%    \cs{everypar}), this will not happen overnight. For that reason
+%    support for this legacy method is retained.}
+%
+%    At the end of the paragraph it would be great if we could use a
+%    similar trick. However, due to the fact that \TeX{} inserts the
+%    token \cs{par} (that doesn't have a defined meaning) we can't hide
+%    \enquote{the real thing\textsuperscript{TM}} and offer the
+%    package an indistinguishable alternate.
+%
+%    Fortunately, \LaTeX{} has already redefined \cs{par} for its own
+%    purposes. As a result there aren't many packages that attempt to
+%    change \cs{par}, because without a lot of extra care that would
+%    fail miserably. But bottom line, if you load a package that
+%    alters \cs{par} then the end of paragraph hooks are most likely
+%    not executing while that redefinition is
+%    active.\footnote{Similarly to the \cs{everypar} situation, the
+%    remedy is that such packages stop doing this and instead add
+%    their alterations into the paragraph hooks now provided.}
+%
+%
+%
+% \subsection{The provided hooks}
+%
+%
+%  \begin{variable}{para/before,
+%                   para/begin,
+%                   para/end,
+%                   para/after
+%                 }
+%    The following four public hooks are defined and executed for
+%    each paragraph:
+%    \begin{description}
+%
+%    \item[\hook{para/before}]
+%
+%      This hook is executed after the kernel hook
+%      \cs{@kernel@before@para@before} (discussed below) in vertical
+%      mode immediately after \TeX{} has contributed \cs{parskip} to
+%      the vertical list and before the actual paragraph processing in
+%      horizontal mode starts.
+%
+%      This hook should either not produce any typeset material or add
+%      only vertical material. If it starts a paragraph an error is
+%      generated. The reason is that we are in the starting process of
+%      processing a paragraph and so this would lead to endless
+%      recursion.\footnote{One could allow it but only if the newly
+%      started paragraph is processed without any hooks. Furthermore
+%      correct spacing would be a bit of a nightmare so for now this
+%      is forbidden.}
+%
+%    \end{description}
+%  \end{variable}
+%
+%    \vspace{-\bigskipamount}
+%
+%    \begin{description}
+%
+%    \item[\hook{para/begin}]
+%
+%      This hook is executed after the kernel hook
+%      \cs{@kernel@before@para@begin} (discussed below) in horizontal
+%      mode immediately before the indentation box is placed (if there
+%      is any, i.e., if the paragraph hasn't been started with
+%      \cs{noindent}).
+%
+%      The indentation box to be typeset is available to the hook as
+%      \cs{IndentationBox} and its automatic placement (after the hook is
+%      executed) can be prevented through \cs{SuppressIndentationBox}.
+%
+%      If not suppressed, then the indentation is typeset directly
+%      after the hook execution by something equivalent to
+%      \cs{box}\cs{IndentationBox} followed by the current content of
+%      the token register \cs{everypar} as it is available to the
+%      kernel or to packages (that run some legacy code).
+%
+%      One has to be careful not to add any code to the hook that
+%      starts its own paragraph (e.g., by adding a \cs{parbox} or a
+%      \cs{marginpar} inside) because that would call the hook inside
+%      again (as a new paragraph is started there) and thus lead to an
+%      endless recursion ending only after exhausting the available
+%      memory. This can only be done by making sure that is not
+%      executed for the inner paragraphs (or at least not recursively
+%      forever).
+%
+%
+%    \item[\hook{para/end}]
+%
+%      This hook is executed at the end of a paragraph when \TeX{} is
+%      ready to return to vertical mode and after it has removed the
+%      last horizontal glue (but not kern) placed on the horizontal
+%      list. The code is still executed in horizontal mode so it is
+%      possible to add further horizontal material at this point, but
+%      it should not alter the mode (even a temporary exit from
+%      horizontal mode would create chaos---any attempt will cause an
+%      error message)! After the hook has ended the kernel hook
+%      \cs{@kernel@after@para@end} is executed and then \TeX{} returns to
+%      vertical mode.
+%
+%      The hook is offered as public hook, but because of the
+%      requirement to stay within horizontal mode one needs to be
+%      careful in what is placed into the hook.\footnote{Maybe we
+%      should guard against that, but it would be rather tricky to
+%      implement as mode changes can happen across group boundaries so
+%      one would need to keep a private stack just for that. Well,
+%      something to ponder.}
+%
+%      This hook is implemented as a reversed hook.
+%
+%    \item[\hook{para/after}]
+%
+%      This hook is executed directly after \TeX{} has returned to
+%      vertical mode and after any material that migrated out of the
+%      horizontal list (e.g., from a \cs{vadjust}) has processed.
+%
+%      This hook should either not produce any typeset material or add
+%      only vertical material.
+%      However, for this hook starting a new paragraph is not a
+%      disaster so that it isn't prevented.
+%
+%      This hook is implemented as a reversed hook.
+%
+%      Once that hook code has been processed the kernel hook
+%      \cs{@kernel@after@para@after} is executed as the final action
+%      of the paragraph processing.
+%
+%    \end{description}
+%
+%  \begin{variable}{\@kernel@before@para@before,
+%                   \@kernel@after@para@after,
+%                    \@kernel@before@para@begin,
+%                   \@kernel@after@para@end,
+%                  }
+%    As already mentioned above there are also four kernel hooks that
+%    are executed at the start and end of the processing.
+%    \begin{description}
+%
+%    \item[\cs{@kernel@before@para@before}]
+%       For future extensions, not currently used by the kernel.
+%
+
+%    \item[\cs{@kernel@after@para@after}]
+%       For future extensions, not currently used by the kernel.
+%
+%
+%    \item[\cs{@kernel@before@para@begin}]
+%
+%      Used by the kernel to implement tagging. This hook is executed
+%      at the very beginning of a paragraph after \TeX{} has switched to
+%      horizontal mode but before any indentation box got added or any
+%      \cs{everypar} was run.
+%
+%      It should not generate typeset material that could alter the
+%      position.  Note that it should never leave hmode, otherwise you
+%      will end with a loop! We could guard against this, but since it
+%      is an internal kernel hook that shouldn't be touched this isn't
+%      checked.
+%    \end{description}
+%  \end{variable}
+%
+%    \vspace{-\bigskipamount}
+%
+%    \begin{description}
+%
+%    \item[\cs{@kernel@after@para@end}]
+%
+%      Used by the kernel to implement tagging. It is executed
+%      directly after the public \hook{para/end} hook. After it there
+%      is a quick check that we are still in horizontal mode, i.e.,
+%      that the public hook has not mistakenly ended horizontal mode
+%      prematurely (this is an incomplete check just testing the mode
+%      and could perhaps be improved (at the cost of speed)).
+%
+%    \end{description}
+%
+%
+% \subsection{Altered and newly provided commands}
+%
+% \begin{function}{\par,\endgraf,\para_end:}
+%    An explicit request for ending a paragraph is known in plain
+%    \TeX{} under the name \cs{endgraf} where it simply calls the
+%    paragraph primitive (regardless of what \cs{par} may have as its
+%    current definition). In \LaTeX{} \cs{endgraf} with that behavior
+%    was also made available.
+%
+%    With the new paragraph handling in \LaTeX{}, ending a paragraph
+%    means a bit more than just calling the engine's paragraph
+%    builder: the process also has to add any hook code for the end of
+%    a paragraph. Thus
+%    \cs{endgraf} was changed to provide this additional functionality
+%    (and so by extension \cs{par} subject to its current meaning).
+%
+%    The \pkg{expl3} name for the functionality is \cs{para_end:}.
+% \end{function}
+%
+% \begin{quote}
+%    \textbf{Note:} \em The next two commands are still under
+%    discussion and may slightly change their semantics (as described
+%    in the document) and/or their names between now and the 2021
+%    Spring release!
+% \end{quote}
+%
+% \begin{function}{\SuppressIndentationBox,\para_suppress_indentation:}
+%    Inside the \hook{para/begin} hook one can use this command to
+%    suppress the indentation box at the start of the
+%    paragraph. (Technically it is possible to use this command
+%    outside the hook as well, but this should not be relied upon.)
+%    The box itself remains available for use.
+%
+%    The \pkg{expl3} name for the function is \cs{para_suppress_indentation:}.
+% \end{function}
+%
+% \begin{variable}{\IndentationBox,\g_para_indentation_box}
+%    The box register holding the indentation box for the paragraph is
+%    available for inspection (or changes) inside hooks. It remains
+%    available even if the \cs{SuppressIndentationBox} command was
+%    used; in that case it  will just not be automatically placed.
+%
+%    The \pkg{expl3} name for the box register is \cs{g_para_indentation_box}.
+% \end{variable}
+%
+%
+%
+%
+% \subsection{Examples}
+%
+%    None of the examples in this section are meant for real use as
+%    they are far too simpleminded  but they should give some ideas of
+%    what could be possible if a bit more care is applied.
+%
+% \subsubsection{Testing the mechanism}
+%
+%    The idea is to output for each paragraph encountered some
+%    information: a paragraph sequence number, a level number in roman
+%    numerals, the environment in which this paragraph appears, and
+%    the line number where the start or end of the paragraph is, e.g.,
+%    something like
+%\begin{verbatim}
+%  PARA: 1-i start (document env. on input line 38)
+%  PARA: 1-i end   (document env. on input line 38)
+%  PARA: 2-i start (document env. on input line 40)
+%  PARA: 3-ii start (minipage env. on input line 40)
+%  PARA: 3-ii end   (minipage env. on input line 40)
+%  PARA: 2-i end   (document env. on input line 41)
+%\end{verbatim}
+%    As you can see paragraph 2 starts on line 40 and ends on 41 and
+%    inside a minipage started paragraph 3 (start and end on line 40).
+%    If you run this on some document you will find that \LaTeX{}
+%    considers more things \enquote{a paragraph} than you have
+%    probably thought.
+%
+%    This was generated by the following hook code:
+%\begin{verbatim}
+%  \newcounter{paracnt}         % sequence counter
+%  \newcounter{paralevel}       % level counter
+%\end{verbatim}
+%
+%    To support paragraph nesting we need to maintain a stack of the
+%    sequence numbers. This is most easily done using \pkg{expl3}
+%    functions, so we switch over. This is not a very general
+%    implementation, just enough for what we need and a bit of
+%    \LaTeXe{} thrown in as well. When popping the result gets stored
+%    in \cs{paracntvalue} and the \cs{ERROR}  should never happen
+%    because it means we have tried to pop from an empty stack.
+%\begin{verbatim}
+%  \ExplSyntaxOn
+%  \seq_new:N \g_para_seq
+%  \cs_new:Npn \ParaPush
+%    {\seq_gpush:No  \g_para_seq {\the\value{paracnt}}}
+%  \cs_new:Npn \ParaPop  {\seq_gpop:NNF  \g_para_seq \paracntvalue \ERROR }
+%  \ExplSyntaxOff
+%\end{verbatim}
+%    At the start of the paragraph increment both sequence counter and
+%    level and also save the then current sequence number on our stack.
+%\begin{verbatim}
+%  \AddToHook{para/begin}{%
+%    \stepcounter{paracnt}\stepcounter{paralevel}%
+%    \ParaPush
+%\end{verbatim}
+%    To display the sequence number we \cs{typeout} the current
+%    sequence and level number. The command \cs{@currenvir} gives us
+%    the current environment and \cs{on@line} produces a space and
+%    the current input line number.
+%\begin{verbatim}
+%    \typeout{PARA: \arabic{paracnt}-\roman{paralevel} start
+%      (\@currenvir\space env.\on@line)}%
+%\end{verbatim}
+%    We also typeset the sequence number as a tiny red number in a box
+%    that takes up no horizontal space. This helps us seeing where
+%    \LaTeX{} sees the start and end of the paragraphs in the
+%    document.
+%\begin{verbatim}
+%    \llap{\color{red}\tiny\arabic{paracnt}\ }%
+%  }
+%\end{verbatim}
+%
+%   At the end of the paragraph we display sequence number and
+%    level again. The level counter has the correct value but we need
+%    to retrieve the right sequence value by popping it off the stack
+%    after which it is available in \cs{paracntvalue} the way we have
+%    set this up above.
+%\begin{verbatim}
+%  \AddToHook{para/end}{%
+%    \ParaPop
+%    \typeout{PARA: \paracntvalue-\roman{paralevel} end \space\space
+%      (\@currenvir\space env.\on@line)}%
+%\end{verbatim}
+%    We also typeset again a tiny red number with that value, this
+%    time sticking out to the right.\footnote{Note that this can alter
+%    the document pagination, because a paragraph ending in a display
+%    (e.g., an equation) will get an extra line---in that case our tiny number
+%    has an effect even though it doesn't take up any space, because
+%    it paragraph is no longer empty and thus isn't dropped!}
+%    We also decrement the level counter since our level has finished.
+%\begin{verbatim}
+%    \rlap{\color{red}\tiny\ \paracntvalue}%
+%    \addtocounter{paralevel}{-1}%
+%  }
+%  \makeatother
+%\end{verbatim}
+%
+%
+%
+% \subsubsection{Mark the first paragraph of each \env{itemize}}
+%
+%    The code for this is rather simple. We apply  hook code that is
+%    executed only once inside a hook that is executed at the begin of
+%    each \env{itemize}. We explicitly change the color back and
+%    forth so that we don't introduce grouping around the paragraph.
+%\begin{verbatim}
+%  \AddToHook{env/itemize/begin}{%
+%    \AddToHookNext{para/begin}{\color{blue}}%
+%    \AddToHookNext{para/end}{\color{black}}%
+%  }
+%\end{verbatim}
+%    As a result the first paragraph of each \env{itemize} will appear
+%    in blue.
+%
+%
+% \StopEventually{\setlength\IndexMin{200pt}  \PrintIndex  }
+%
+%
+% \section{The Implementation}
+%
+%    \begin{macrocode}
+%<*2ekernel>
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+%<@@=para>
+\ExplSyntaxOn
+%    \end{macrocode}
+
+
+%
+%
+% \subsection{Providing hooks for paragraphs}
+%
+%
+%  \begin{macro}{para/before,para/after,para/begin,para/end}
+%    The public hooks. They are implemented as a paired set of hooks.
+%    \begin{macrocode}
+\hook_new_pair:nn{para/before}{para/after}
+\hook_new_pair:nn{para/begin}{para/end}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%  \begin{macro}{\@kernel@before@para@before,
+%                \@kernel@after@para@after,
+%                \@kernel@before@para@begin,
+%                \@kernel@after@para@end}
+%    The corresponding kernel hooks (for tagging and future extensions).
+%    \begin{macrocode}
+\let \@kernel@before@para@before \@empty
+\let \@kernel@before@para@begin  \@empty
+\let \@kernel@after@para@end     \@empty
+\let \@kernel@after@para@after   \@empty
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%
+%
+%  \begin{macro}{\g_@@_standard_everypar_tl}
+%    Whenever \TeX{} starts a paragraph it inserts first an
+%    indentation box and then executes the tokens stored in
+%    \cs{tex_everypar:D} (known to \LaTeX{} as \cs{everypar}). We
+%    alter this behavior slightly here, so that hooks are added
+%    into the right place. Otherwise the process change remains
+%    transparent to any legacy code for this space.
+%
+%    We keep the standard code to be used by \cs{tex_everypar:D} in a
+%    separate token list because we have to switch back and forth
+%    for error recovery and so altering \cs{tex_everypar:D}  all the
+%    time should be a tiny bit faster.
+%    \begin{macrocode}
+\tl_new:N \g_@@_standard_everypar_tl
+%    \end{macrocode}
+%    Here is now its definition:
+%    \begin{macrocode}
+\tl_gset:Nn \g_@@_standard_everypar_tl {
+%    \end{macrocode}
+%    First we remove the indentation box and store it in
+%    \cs{g_para_indentation_box}. If there was none because the paragraph
+%    was started by \cs{noindent} the box register will be void.
+%    \begin{macrocode}
+  \box_gset_to_last:N \g_para_indentation_box
+%    \end{macrocode}
+%
+%    This will make the newly started horizontal list empty, so if we
+%    stop it now and return to vertical mode it will be dropped by
+%    \TeX{}. We do that but inside a group so that any \cs{parshape}
+%    settings will not get lost as we need them for later.
+%    \begin{macrocode}
+  \group_begin:
+    \tex_par:D
+  \group_end:
+%    \end{macrocode}
+%    We then change \cs{tex_everypar:D} to generate an error so that
+%    we can detect and report if the \hook{para/before} hook illegally
+%    changed out of vmode.
+%    \begin{macrocode}
+  \tex_everypar:D { \__kernel_msg_error:nnnn {para}{mode}{before}{vertical} }
+  \@kernel@before@para@before
+  \hook_use:n {para/before}
+%    \end{macrocode}
+%    Assuming the hooks have been well behaved it is time to return to
+%    horizontal mode and start the paragraph in earnest. We already
+%    have the indentation box saved away so we now have to restart the
+%    paragraph with an empty \cs{tex_everypar:D} and with
+%    \cs{tex_noindent:D}. And we need to make sure not to get another
+%    \cs{parskip} or rather (since we can't prevent that) that it is
+%    of zero size.
+%    \begin{macrocode}
+  \group_begin:
+    \tex_everypar:D {}
+    \skip_zero:N \tex_parskip:D
+    \tex_noindent:D
+  \group_end:
+%    \end{macrocode}
+%    That brings us back to the start of the horizontal list but we
+%    need to change \cs{tex_everypar:D} back to its normal content in
+%    case there are nested paragraphs coming up.
+%    \begin{macrocode}
+  \tex_everypar:D{\g_@@_standard_everypar_tl}
+%  \showthe\tex_everypar:D
+%    \end{macrocode}
+%    Then we set up \cs{@@_handle_indent:} to reinsert the indentation
+%    box later. This can be undone via \cs{SuppressIndentationBox}
+%    inside the hook(s).
+%    \begin{macrocode}
+  \cs_set_eq:NN \@@_handle_indent: \@@_add_indentation_box:
+%    \end{macrocode}
+%
+%    This is followed by executing the kernel and the public hook. The
+%    kernel hook is there to enable tagging.
+%    \begin{macrocode}
+  \@kernel@before@para@begin
+  \hook_use:n {para/begin}
+%    \end{macrocode}
+%    If we aren't in horizontal mode any longer the hooks above misbehaved.
+%    \begin{macrocode}
+  \if_mode_horizontal: \else:
+    \__kernel_msg_error:nnnn {para}{mode}{begin}{vertical} \fi:
+%    \end{macrocode}
+%    Finally we reinsert the indentation box (unless suppressed) and
+%    then call \cs{everypar} the way legacy \LaTeX\ code expects it.
+%
+%    However, adding the public \cs{everypar} is a bit tricky (see below) so
+%    we add that later, and indirectly.
+%    \begin{macrocode}
+  \@@_handle_indent:
+% \the \everypar           % <--- done differently
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%  \begin{macro}[int]{\tex_everypar:D}
+%    \cs{tex_everypar:D} then only has to execute
+%    \cs{g_@@_standard_everypar_tl} by default.
+%    \begin{macrocode}
+\tex_everypar:D{\g_@@_standard_everypar_tl}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%  \begin{macro}[int]{\everypar}
+%
+%    Tokens inserted at the beginning of the paragraph are placed into
+%    \cs{everypar} inside legacy \LaTeX{} code, e.g., by the list
+%    environments or by headings to handle \cs{clubpenalty}, etc. Now
+%    this isn't any longer the primitive but simply a toks register
+%    used in the code above but to legacy \LaTeX{} code that is
+%    transparent.
+%
+%    There is, however, a problem: a handful packages use exactly the
+%    same trick and replace the primitive with a token register and
+%    call the token register inside the renamed primitive. That is
+%    they assume that \cs{everypar} is the primitive and that it will
+%    still be called at the start of the paragraph even if renamed.
+%
+%    But if we have already replaced it by a token register then all
+%    they do is to give that token register a new name. Thus our code
+%    in \cs{tex_everypar:D} would call \cs{everypar} (which is their
+%    now token register) and the code that they added ends up in our
+%    token register which is then never used at all. A bit mind
+%    boggling I guess.
+%
+%    So what we have to do is not to call the token register
+%    \cs{everypar} by its name inside \cs{tex_everypar:D} but by using
+%    its actual register number.
+%    \begin{macrocode}
+\newtoks \everypar
+%    \end{macrocode}
+%
+%    After we have allocated a new toks register with the name
+%    \cs{everypar} the actual register number is available (briefly)
+%    inside \cs{allocationnumber}. So instead of \cs{the}\cs{everypar}
+%    we have to put \cs{the}\cs{toks}\meta{allocated number} at the end of
+%    \cs{tex_everypar:D}.
+%
+%    So what remains doing is to append a few tokens to the token list
+%    \cs{g_@@_standard_everypar_tl} which we do now. We use \texttt{x}
+%    expansion here to get the value of \cs{allocationnumber} in, all
+%    the other tokens should not be expanded at this point.
+
+%    One important point here is to terminate the register allocation
+%    number with a real space. This space will get swallowed up when
+%    the number is read. Anything else, such as \cs{scan_stop:} would
+%    remain in the input and that would mean that it would interfere
+%    with \cs{everypar} code that attempts to scan ahead to see how
+%    the paragraph text starts.
+%    \begin{macrocode}
+\tl_gput_right:Nx \g_@@_standard_everypar_tl {
+    \exp_not:N \the
+    \exp_not:N \toks
+    \the \allocationnumber
+    \c_space_tl
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\g_para_indentation_box}
+%    For managing the indentation we need to provide a public
+%    accessible box register
+%    \begin{macrocode}
+\box_new:N \g_para_indentation_box
+%    \end{macrocode}
+%  \end{macro}
+
+%  \begin{macro}{\@@_handle_indent:,\@@_add_indentation_box:}
+%    Adding (typesetting) the indent box is straight forward, the
+%    default action for is \cs{@@_handle_indent:} is
+%    \cs{@@_add_indentation_box:}.
+%    \begin{macrocode}
+\cs_new:Npn \@@_add_indentation_box: {
+  \box_use_drop:N \g_para_indentation_box
+}
+\cs_new_eq:NN \@@_handle_indent: \@@_add_indentation_box:
+%    \end{macrocode}
+%     The declaration \cs{para_suppress_indentation:} (or
+%    \cs{SuppressIndentationBox}) changes that to do nothing.
+%    \begin{macrocode}
+\cs_new:Npn \para_suppress_indentation: {
+  \cs_set_eq:NN \@@_handle_indent: \prg_do_nothing:
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\IndentationBox,\SuppressIndentationBox}
+%    The \LaTeXe{} names for the indentation box and for suppressing it
+%    for use in the \hook{para/begin} hook.
+%    \begin{macrocode}
+\cs_set_eq:NN \IndentationBox \g_para_indentation_box
+\cs_set_eq:NN \SuppressIndentationBox \para_suppress_indentation:
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%
+%
+%
+%  \begin{macro}{\para_end:}
+%    Adding hooks to the end of a paragraph is similar but here we
+%    need to alter the command that is used by \TeX{} to end horizontal
+%    mode and return to vertical mode, i.e., \cs{par}.
+%
+%    This is a bit more complicated as this command can appear anywhere
+%    either explicitly or implicitly added by \TeX{} in certain
+%    situations:
+%    \begin{itemize}
+%    \item
+%      when using \cs{par} in the code or the document
+%    \item
+%      when using a blank line (which is converted to \cs{par})
+%    \item
+%      when \TeX{} finds any commands incompatible with horizontal
+%      mode it issues a \cs{par} and then rereads the command.
+%    \end{itemize}
+%
+%    Unfortunately, \TeX{} has some (these days) unnecessary
+%    optimization: if a \cs{vbox} ends and \TeX{} is still in
+%    horizontal mode it simply exercises the paragraph builder instead
+%    of issuing a \cs{par}. It is therefore necessary for \LaTeX{} to
+%    ensure that this case doesn't happen and all boxes internally
+%    have a \cs{par} command at their end.
+%
+%    This \cs{par} may or may not run the ``par primitive'' (which is
+%    always available as \cs{tex_par:D} in \pkg{expl3}); it is
+%    permissible to have a changed meaning and it is in fact changed
+%    by \LaTeX{} in various ways at various points inside
+%    \texttt{latex.ltx}.  For this \LaTeXe{} code has the following
+%    conventions: \cs{@@@@par} and \cs{endgraf} both refer to the
+%    default meaning (in the past this was the initex primitive) while
+%    \cs{par} is the current meaning which may does something else.
+%
+%
+%    We are now going to change this default meaning to run
+%    \cs{para_end:} instead, which ultimately executes the initex
+%    primitive but additionally adds our hooks when appropriate.
+%    This way the change is again transparent to the legacy \LaTeXe{}
+%    code.
+%
+%    In most cases \cs{para_end:} should behave exactly like the
+%    primitive and we achieve this by simply expanding it to the
+%    primitive which is available to us as \cs{tex_par:D}. This way we
+%    don't have to care about whether \TeX{} just does nothing (e.g.,
+%    if in vertical mode already) or generate an error, etc.
+%    \begin{macrocode}
+\cs_new_protected:Npn \para_end: {
+%    \end{macrocode}
+%
+%    The only case we care about is when we are in horizontal mode
+%    (i.e., doing typesetting) and not also in inner mode (i.e.,
+%    making paragraphs and not building an \cs{hbox}.
+%    \begin{macrocode}
+%  \bool_lazy_and:nnT
+%       { \mode_if_horizontal_p: }
+%       { \bool_not_p:n { \mode_if_inner_p: } }
+%       { ...
+%    \end{macrocode}
+%    Since this is executed for each and every paragraph in a document
+%    we try to stay a fast as possible, So we are aren't using the
+%    above construct but two conditionals instead. Using low-level
+%    \cs{if_mode...} conditions would be even faster but has the
+%    danger to conflict with conditionals in the user hooks.
+%    \begin{macrocode}
+  \mode_if_horizontal:TF {
+    \mode_if_inner:F {
+%    \end{macrocode}
+%    In that case the action of the primitive would be to remove the
+%    last glue (not kern) from the horizontal list constructed to form
+%    a paragraph then append the a penalty of 10000 and the
+%    \cs{parfillskip} at the end and pass the whole list to the
+%    paragraph builder which breaks it into lines and \TeX{} then
+%    returns to vertical mode.
+%
+%    What we want to do instead is to add our hook code at the end of
+%    the horizontal list before that happens and the code is passed to
+%    the paragraph builder. If there was a glue item at the end then
+%    it should get removed before the hook code gets added so we have
+%    to arrange for its removal ourselves.
+%
+%    There is not much point in checking if there was really a glue
+%    item at the end of the horizontal list, instead we simply try to
+%    remove one using \cs{tex_unskip:D}, if there wasn't one this will
+%    do nothing.
+%    \begin{macrocode}
+         \tex_unskip:D
+%    \end{macrocode}
+%    The we execute the public hook (which may add final typesetting
+%    material) followed by the kernel hook we need for adding tagging
+%    support. None of this is supposed to change the mode---at the
+%    moment we make only a very simple test for this, more devious
+%      changes go unnoticed, but too bad, that will then probably
+%      badly backfire.
+%    \begin{macrocode}
+         \hook_use:n{para/end}
+         \@kernel@after@para@end
+         \mode_if_horizontal:TF {
+%    \end{macrocode}
+%    The final action (before getting to the point where
+%    \cs{tex_par:D} is called) is to add a kern item so that the
+%    primitive is prevented from removing glue (if there was some). If
+%      we don't do this and the
+%    horizontal list ended in several glue items we would end up  with
+%    removing two instead of just the last one, which would be wrong.
+%    We use a kern as that is minimally faster.
+%
+%    There is however one other \TeX{} optimization that hurts: in a
+%    sequence like this \verb=$$ ... $$ \par=  \TeX{} will be in
+%    horizontal mode after the display, ready to receive further
+%    paragraph text, but since the \cs{par} follows immediately there
+%    is a ``null'' paragraph at the end and \TeX{} simply throws that
+%    away. The space between \verb=$$= and \cs{par} got already
+%    dropped during the display processing so the \cs{par} is not
+%    removing any space and appending \cs{parfillskip}, instead it
+%    simply goes silently to vmode. Now if we would had added something (to
+%    prevent glue removal) that would look to \TeX{} like material
+%    after the display and so we would end up with an empty paragraph
+%    just containing \cs{parfillskip}.
+%
+%    We therefore check if the current hlist is empty
+%    (\cs{tex_lastnodetype:D} has the value \texttt{-1} and
+%    only if not we add our kern.
+%    \begin{macrocode}
+           \if_int_compare:w 0 < \tex_lastnodetype:D
+             \tex_kern:D \c_zero_dim
+           \fi:
+%    \end{macrocode}
+%    To run the \hook{para/after} hook we first end the
+%    paragraph. This means that the \cs{tex_par:D} at the very end is
+%    unnecessary but executing it there unnecessarily is better than
+%    having code that test for all the different mode possibilities.
+%    \begin{macrocode}
+           \tex_par:D
+           \hook_use:n{para/after}
+           \@kernel@after@para@after
+         }
+%    \end{macrocode}
+%    If we haven't been in horizontal mode then the earlier hook
+%    \hook{para/end} is at fault and we report that.
+%    \begin{macrocode}
+         { \__kernel_msg_error:nnnn {para}{mode}{end}{horizontal} }
+%    \end{macrocode}
+%    Finally close out the nested conditionals.
+%    \begin{macrocode}
+    }
+  }  
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+  \tex_par:D
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%    This ends the \texttt{para} module code.
+%    \begin{macrocode}
+%<@@=>
+%    \end{macrocode}
+%
+%  \begin{macro}{\par,\endgraf}
+%  \begin{macro}[int]{\@@par}
+%
+%    Having the new default definition for \cs{par} we also have to
+%    set it up so that it gets used. This is needed in three places
+%    \cs{par}, \cs{@@par} (to which \LaTeX{} resets \cs{par}
+%    occasionally) and \cs{endgraf} which is another name for the
+%    ``default'' action of \cs{par}.
+%    \begin{macrocode}
+\cs_set_eq:NN \par     \para_end:
+\cs_set_eq:NN \@@par   \para_end:
+\cs_set_eq:NN \endgraf \para_end:
+%    \end{macrocode}
+%  \end{macro}
+%  \end{macro}
+%
+%    While this is not integrated properly into the format we have to
+%    redo the \cs{everypar} setting from the kernel, otherwise that
+%    gets lost (as it happens before that file is loaded).
+%    \begin{macrocode}
+\everypar{\@nodocument} %% To get an error if text appears before the
+%    \end{macrocode}
+%
+%
+%   \subsection{The error messages}
+%
+%    Well, one really, first argument is the hook name second the mode
+%    it should have stayed in but didn't.
+%    \begin{macrocode}
+\__kernel_msg_new:nnnn {para} {mode}
+  {
+    Illegal~mode~ change~ in~ hook~ 'para/#1'.\\
+    Hook~ code~ did~ not~ remain~ in~ #2~ mode.
+  }
+  {
+    Paragraph~ hooks~ cannot~ change~ the~ TeX~ mode~ without~ causing~
+    endless~ recursion.~ The~ hook~ code~ in~ 'para/#1'~ needs~ to~ stay~
+    in~ #2~ mode,~ but~ it~ didn't.~ Examine~ the~ hook~
+    code~ with~ \ShowHook~ to~ find~ the~ issue.
+  }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\ExplSyntaxOff
+%    \end{macrocode}
+%
+%  \subsection{Kernel corrections}
+%
+%    These corrections/changes are already part of the 2021/05
+%    release, i.e., but for testing with older releases they have been
+%    included here for now. So this section will vanish soon.
+%
+%
+%    Marginpar boxes are missing a final internal \cs{par}.
+%    \begin{macrocode}
+\IfFormatAtLeastTF{2021/05/01}{}
+{
+\long\def \@savemarbox #1#2{%
+  \global\setbox #1%
+    \color@vbox
+      \vtop{%
+        \hsize\marginparwidth
+        \@parboxrestore
+        \@marginparreset
+        #2\par                    % <-- needed
+        \@minipagefalse
+        \outer@nobreak
+        }%
+    \color@endbox
+}
+%    \end{macrocode}
+%
+%    Two sample definitions for the kernel hooks to help a bit with
+%    tracing.
+%    \begin{macrocode}
+\newcounter{paracnt}
+\def\@kernel@before@para@begin{%
+  \stepcounter{paracnt}%
+  \typeout{PARA: \arabic{paracnt} start
+    (\@currenvir\space level\on@line)}%
+}
+\def\@kernel@after@para@end  {%
+  \typeout{PARA: \arabic{paracnt} end \space\space
+    (\@currenvir\space level\on@line)}%
+  \addtocounter{paracnt}{-1}%
+}
+%    \end{macrocode}
+%
+%
+%    The next lines belong in the kernel and just make sure that  we
+%    avoid the these days unnecessary optimization that \TeX{} doesn't
+%    call on \cs{par} if a vertical box ends in hmode. Instead \TeX{}
+%    directly calls the par builder in that case :-(.
+%    \begin{macrocode}
+\let\color@begingroup\begingroup
+\def\color@endgroup{\endgraf\endgroup}
+\def\color@setgroup{\color@begingroup}  % \def\color@setgroup{\color@begingroup\set@color}
+\def\color@hbox{\hbox\bgroup\color@begingroup}
+\def\color@vbox{\vbox\bgroup\color@begingroup}
+\def\color@endbox{\color@endgroup\egroup}
+}
+%    \end{macrocode}
+%
+%
+%
+%    \begin{macrocode}
+%<*2ekernel>
+%    \end{macrocode}
+%
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\endinput
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+
+%%%% unused as hok was dropped
+
+% \subsubsection{Put the first word of each paragraph in an \cs{fbox} and append
+%    a \P{} sign at the end of the paragraph}
+%
+%    We make the assumption that the first word ends in a space so
+%    that we can grab it easily (which
+%    is of course not quite right). So here is the code for that.
+%\begin{verbatim}
+%  \def\firstwordboxed#1 {\fbox{#1} }
+%\end{verbatim}
+%    Installing that is then just a matter of putting it into the right
+%    hook. Since we don't want to box the indentation (or what comes
+%    from \cs{everypar} we shouldn't use \hook{para/begin} but
+%    \hook{para/textbegin}.
+%    Adding the \P{} is equally simple.
+%\begin{verbatim}
+%  \AddToHook{para/textbegin}{\firstwordboxed}
+%  \AddToHook{para/end}{\P}
+%\end{verbatim}
+%    While this will work more or less flawless (if you accept that it
+%    will pick up any punctuation after the first word), it will fail
+%    in at least two cases.
+%    \begin{itemize}
+%    \item Single word paragraphs ending with \cs{par} instead of an
+%    empty line will blow up because the \cs{par} will be picked up as
+%    part of the argument and error as our \cs{firstwordboxed} doesn't
+%    accept a \cs{par} not being long. That is actually good, because
+%    picking it up would be worse: it would get ignored inside
+%    \cs{fbox} and so the paragraph would be combined with the next
+%    (or worse).
+%
+%    \item The second problem is, of course, that sticking it into
+%    every \hook{para/textbegin} means it get applied to places like
+%    \cs{section} which is not really what you want. So some more
+%    elaborate mechanism would be necessary---a task for another rainy
+%    day.
+%    \end{itemize}
+%
+%    There is one other point to note here. The \cs{firstwordboxed} is
+%    expected to scan ahead. So can that kind of code be placed into a
+%    hook? The answer is a kind of yes and no.
+
+%    Hooks can receive code from different places, but obviously only
+%    one chunk of code can do some scanning ahead, the one that comes
+%    last. Any hook code in a different position would see any
+%    following code from later chunks as part of the scanning which
+%    may or may not be a problem. In fact, even in our simple example,
+%    the argument picked up by \cs{firstwordboxed} isn't really the
+%    first word of the paragraph. It is that but in front of it there
+%    is also the code responsible for running
+%    \verb=\AddTohookNext{para/textbegin}=. As long as this is not
+%    doing anything harmful it doesn't hurt in this case, but it
+%    clearly shows that this example is not as  simple as it
+%    claims to be and on the whole we have to conclude that hooks
+%    aren't really meant to do such scanning or at least not without a
+%    lot of precaution.
+%
diff --git a/Master/texmf-dist/source/latex-dev/base/ltpictur.dtx b/Master/texmf-dist/source/latex-dev/base/ltpictur.dtx
index 10773f376cf..b958d43760c 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltpictur.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltpictur.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltplain.dtx b/Master/texmf-dist/source/latex-dev/base/ltplain.dtx
index 0b03fd1364d..fa53cc17ece 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltplain.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltplain.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltsect.dtx b/Master/texmf-dist/source/latex-dev/base/ltsect.dtx
index 70106e2e583..29ea142ba6c 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltsect.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltsect.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltshipout.dtx b/Master/texmf-dist/source/latex-dev/base/ltshipout.dtx
index 2ea0a1b6651..565f35f529c 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltshipout.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltshipout.dtx
@@ -1,6 +1,7 @@
 % \iffalse meta-comment
 %%
-%% File: ltshipout.dtx (C) Copyright 2020,2021 Frank Mittelbach, LaTeX Team
+%% Copyright (C) 2020-2021
+%%               Frank Mittelbach, LaTeX Team
 %%
 %
 % This file is part of the LaTeX base system.
@@ -31,8 +32,8 @@
 %%% From File: ltshipout.dtx
 %
 %    \begin{macrocode}
-\providecommand\ltshipoutversion{v1.0d}
-\providecommand\ltshipoutdate{2020/12/06}
+\providecommand\ltshipoutversion{v1.0i}
+\providecommand\ltshipoutdate{2021/01/25}
 %    \end{macrocode}
 %
 %<*driver>
@@ -55,6 +56,9 @@
   }
 \ExplSyntaxOff
 
+\providecommand\InternalDetectionOff{}
+\providecommand\InternalDetectionOn{}
+
 \EnableCrossrefs
 \CodelineIndex
 \begin{document}
@@ -108,11 +112,50 @@
 %    It then stores it in a named box register.  This box can then be
 %    manipulated through a set of hooks after which it is shipped out
 %    for real.
+%
+%    Each shipout that actually happens (i.e., where the material is
+%    not discarded for one or the other reason) is recorded and the
+%    total number is available in a readonly variable and in a
+%    \LaTeX{} counter.
+% \end{function}
+%
+%
+% \begin{function}{\RawShipout}
+%    This command implements a simplified shipout that bypasses the
+%    foreground and background 
+%    hooks, e.g., only \hook{shipout/firstpage} and
+%    \hook{shipout/lastpage} are executed and the total shipout
+%    counters are incremented.
+%
+%    The command doesn't use \cs{ShipoutBox} but its own private box
+%    register so that it can be used inside of shipout hooks to do
+%    some additional shipouts while already in the output routine with
+%    the current page being stored in \cs{ShipoutBox}. It does have
+%    access to \cs{ShipoutBox} if it is used in \hook{shipout/before}
+%    (or \hook{shipout/after}) and can use its content.
+%
+%    It is safe to use it in \hook{shipout/before} or
+%    \hook{shipout/after} but not necessarily in the other
+%    \hook{shipout/...} hooks as they are intended for special
+%    processing.
 % \end{function}
 %
 %  \begin{variable}{\ShipoutBox,\l_shipout_box}
-%    This box register is called \cs{ShipoutBox} (alternatively available via the
-%    L3 name \cs{l_shipout_box}).
+%    This box register is called \cs{ShipoutBox} (alternatively
+%    available via the L3 name \cs{l_shipout_box}).
+%
+%    During the execution of \hook{shipout/before} this box contains
+%    the accumulated material for the page, but not yet any material
+%    added by other shipout hooks.
+%    During execution of \hook{shipout/after}, i.e., after the shipout
+%    has happened, the box also contains any background or foreground
+%    material.
+%
+%    Material from the hooks \hook{shipout/firstpage} or
+%    \hook{shipout/lastpage} is not included (but only used during the
+%    actual shipout) to facilitate reuse of the box data (e.g.,
+%    \hook{shipout/firstpage} material should never be added to a
+%    later page of the output).
 %  \end{variable}
 %
 %
@@ -133,11 +176,11 @@
 %
 % \subsection{Provided hooks}
 %
-%  \begin{variable}{shipout/before,
+%  \begin{variable}{shipout/before,shipout/after,
 %                   shipout/foreground,shipout/background,
 %                   shipout/firstpage,
 %                   shipout/lastpage}
-%    The code offers a number of hooks into which packages (or the
+%    The code for \cs{shipout} offers a number of hooks into which packages (or the
 %    user) can add code to support different use cases.
 %    These are:
 %    \begin{description}
@@ -148,6 +191,20 @@
 %       It can be used to alter that box content or to discard it
 %       completely (see \cs{DiscardShipoutBox} below).
 %
+%       You can use \cs{RawShipout} inside this hook for special use
+%       cases. It can make use of \cs{ShipoutBox} (which doesn't yet
+%       include the background and foreground material).
+%
+%       \textbf{Note:} It is not possible (or say advisable) to try
+%       and use this hook to typeset material with the intention to
+%       return it to main vertical list, it will go wrong and give
+%       unexpected results in many cases---for starters it will appear
+%       after the current page not before or it will vanish or the
+%       vertical spacing will be wrong!
+%    \end{description}
+%  \end{variable}
+%
+%    \begin{description}
 %    \item[\hook{shipout/background}]
 %
 %       This hook adds a picture environment into the background of
@@ -186,9 +243,14 @@
 %       not discarded at the last minute). It should only contain
 %       \cs{special} or similar commands needed to direct post processors
 %       handling the \texttt{.dvi} or \texttt{.pdf} output.\footnotemark
+%  \footnotetext{In
+%         \LaTeXe{} that was already existing, but implemented using a box
+%         register with the name \cs{@begindvibox}.}
 %
 %       ^^A \fmi{not sure it has to be that restrictive.}
 %
+%       This hook is added to the very first page regardless of how it
+%       is shipped out (i.e., with \cs{shipout} or \cs{RawShipout}).
 %
 %    \item[\hook{shipout/lastpage}]
 %
@@ -196,6 +258,7 @@
 %       the output file. It is only executed on the very last page of
 %       the output file ---
 %       or rather on the page that \LaTeX{} believes is the last one.
+%       Again it is executed regardless of the shipout method.
 %
 %       It may not be possible for \LaTeX{} to correctly determine
 %       which page is the last one without several reruns. If this
@@ -203,17 +266,32 @@
 %       extra page to place the material and also request a rerun to
 %       get the correct placement sorted out.
 %
+%    \item[\hook{shipout/after}]
+%
+%       This hook is executed after a shipout has happened. If the
+%       shipout box is discarded this hook is not looked at.
+%
+%       You can use \cs{RawShipout} inside this hook for special use
+%       cases and the main \cs{ShipoutBox} is still available at this
+%       point (but in contrast to \hook{shipout/before} it now
+%       includes the background and foreground material).
+%
+%       \textbf{Note:} Just like \hook{shipout/before} this hook is
+%       not meant to be used for adding adding typeset material back
+%       to the main vertical list---it might vanish or the
+%       vertical spacing will be wrong!
+%
+%
 %    \end{description}
-%  \end{variable}\footnotetext{In
-%         \LaTeXe{} that was already existing, but implemented using a box
-%         register with the name \cs{@begindvibox}.}
 %
 %    As mentioned above the hook \hook{shipout/before} is executed
 %    first and can manipulate the prepared shipout box stored in
 %    \cs{ShipoutBox} or set things up for use in \cs{write} during the
-%    actual shipout. The other hooks are added inside hboxes to the
-%    box being shipped out in the following
-%    order:
+%    actual shipout. It is even run if there was a
+%    \cs{DiscardShipoutBox} request in the document.
+%
+%    The other hooks (except \hook{shipout/after}) are added inside
+%    hboxes to the box being shipped out in the following order:
 %    \begin{center}
 %    \begin{tabular}{ll}
 %       \hook{shipout/firstpage}   & only on the first page \\
@@ -226,14 +304,22 @@
 %    If any of the hooks has no code then that particular no box is
 %    added at that point.
 %
+%    Once the (page) box has been shipped out the \hook{shipout/after}
+%    hook is called (while you are still inside the output routine). It
+%    is not called if the shipout box was discarded.
+%
 %    In a document that doesn't produce pages, e.g., only makes
-%    \cs{typeout}s, none of the hooks are executed (as there is no
+%    \cs{typeout}s, none of the hooks are ever executed (as there is no
 %    \cs{shipout}) not even the \hook{shipout/lastpage} hook.
 %
+%    If \cs{RawShipout} is used instead of \cs{shipout} then only the
+%    hooks \hook{shipout/firstpage} and \hook{shipout/lastpage} are
+%    executed (on the first or last page), all others are bypassed.
 %
-% \subsection{Legacy \LaTeX{} commands}
 %
 %
+% \subsection{Legacy \LaTeX{} commands}
+%
 % \begin{function}{\AtBeginDvi,\AtEndDvi}
 %    \cs{AtBeginDvi} is the existing \LaTeXe{} interface to fill the
 %    \hook{shipout/firstpage} hook. This is not really a good name
@@ -256,12 +342,12 @@
 %
 % \subsection{Special commands for use inside the hooks}
 %
-% \begin{function}{\DiscardShipoutBox,\shipout_discard_box:}
+% \begin{function}{\DiscardShipoutBox,\shipout_discard:}
 %   \begin{syntax}
 %     \cs{AddToHookNext} \texttt{\{shipout/before\} \{...\cs{DiscardShipoutBox}...\}}
 %   \end{syntax}
 %    The \cs{DiscardShipoutBox} declaration (L3 name
-%    \cs{shipout_discard_box:})
+%    \cs{shipout_discard:})
 %    requests that on the next
 %    shipout the page box is thrown away instead of being shipped to
 %    the \texttt{.dvi} or \texttt{.pdf} file.
@@ -272,6 +358,8 @@
 %    Note that if this declaration is used directly in the document it
 %    may depend on the placement to which page it applies, given that
 %    \LaTeX{} output routine is called in an asynchronous manner!
+%    Thus normally one would use this only as part of the
+%    \hook{shipout/before} code.
 %
 %    \fmi{Once we have a new mark mechanism available we can improve
 %    on that and make sure that the declaration applies to the page
@@ -290,12 +378,28 @@
 %    names as given below.
 %
 %
+%
+% \subsection{Provided Lua\TeX\ callbacks}
+% 
+%  \begin{variable}{pre_shipout_filter}
+%    Under Lua\TeX{} the \texttt{pre\_shipout\_filter} Lua callback is
+%    provided which gets called immediately before the shipout primitive gets invoked.
+%    The signature is
+%    \begin{verbatim}
+%     function(<node> head)
+%       return true
+%     end
+%    \end{verbatim}
+%    The \texttt{head} is the list node corresponding to the box to be shipped out.
+%    The return value should always be \texttt{true}.
+%  \end{variable}
+%
 % \subsection{Information counters}
 %
 %
 %  \begin{variable}{\ReadonlyShipoutCounter,\g_shipout_readonly_int}
 %   \begin{syntax}
-%     \cs{ifnum}\cs{ReadOnlyShipoutCounter}\texttt{=...}
+%     \cs{ifnum}\cs{ReadonlyShipoutCounter}\texttt{=...}
 %     \cs{int_use:N} \cs{g_shipout_readonly_int} \texttt{\% expl3 usage}
 %   \end{syntax}
 %    This integer holds the number of pages shipped out up to now
@@ -303,6 +407,7 @@
 %    routine). More precisely, it is incremented only after it is
 %    clear that a page will be shipped out, i.e., after the
 %    \hook{shipout/before} hook (because that might discard the page)!
+%    In contrast \hook{shipout/after} sees the incremented value.
 %
 %    Just like with the \texttt{page} counter its value is
 %    only accurate within the output routine. In the body of the
@@ -310,10 +415,11 @@
 %    asynchronously!
 %
 %    Also important: it \emph{must not} be set, only read. There are
-%    no provisions to prevent that but if you do, chaos will be the
-%    result. To emphasize this fact it is not provided as a \LaTeX{}
-%    counter but as a \TeX{} counter (i.e., a command), so
-%    \cs{Alph}\Arg{\cs{ReadonlyShipoutCounter}} etc, would not work.
+%    no provisions to prevent that restriction, but if you manipulate
+%    it, chaos will be the result. To emphasize this fact it is not
+%    provided as a \LaTeX{} counter but as a \TeX{} counter (i.e., a
+%    command), so \cs{Alph}\verb={=\cs{ReadonlyShipoutCounter}\verb=}=
+%    etc, would not work.
 %  \end{variable}
 %
 %  \begin{variable}{totalpages,\g_shipout_totalpages_int}
@@ -325,7 +431,8 @@
 %    \texttt{totalpages} counter is a \LaTeX{} counter and incremented
 %    for each shipout attempt including those pages that are discarded
 %    for one or the other reason. Again \hook{shipout/before} sees
-%    the counter before it is incremented).
+%    the counter before it is incremented. In contrast
+%    \hook{shipout/after} sees the incremented value.
 %
 %    Furthermore, while it is incremented for each page, its value is
 %    never used by \LaTeX. It can therefore be freely reset or changed by user
@@ -427,6 +534,21 @@
 %    This is the name of the shipout box as \pkg{atbegshi} knows it.
 % \end{function}
 %
+%
+% \begin{function}{\AtBeginShipoutOriginalShipout}
+%    This is the name of the \cs{shipout} primitive as \pkg{atbegshi}
+%    knows it. This bypasses all the mechanisms set up by the \LaTeX{}
+%    kernel and there are various scenarios in which it can therefore
+%    fail. It should only be used to run existing legacy
+%    \pkg{atbegshi} code but not in newly developed applications.
+%
+%    The kernel alternative is \cs{RawShipout} which is integrated
+%    with the \LaTeX{} mechanisms and updates, for example, the
+%    \cs{ReadonlyShipoutCounter} counter. Please use \cs{RawShipout}
+%    for new code if you want to bypass the before, foreground and
+%    background hooks.
+% \end{function}
+%
 % \begin{function}{\AtBeginShipoutInit}
 %   By default \pkg{atbegshi} delayed its action until
 %    \verb=\begin{document}=.  This command was forcing it in an earlier
@@ -591,6 +713,41 @@
 %  \end{macro}
 %
 %
+%  \begin{macro}{\l_@@_raw_box}
+%    The \cs{RawShipout} gets its own box but it is internal as there
+%    is no hook manipulation for it.
+%    \begin{macrocode}
+\box_new:N  \l_@@_raw_box
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\@@_finalize_box:}
+%    For Lua\TeX{} invoke the \texttt{pre\_shipout\_filter} callback.
+%  \changes{v1.0i}{2021/01/22}{Add \texttt{pre\_shipout\_filter} Lua callback}
+%    \begin{macrocode}
+\sys_if_engine_luatex:TF
+  {
+    \newluafunction \@@_finalize_box:
+    \exp_args:Nx \everyjob {
+      \exp_not:V \everyjob
+      \exp_not:N \lua_now:n {
+        luatexbase.create_callback('pre_shipout_filter', 'list')
+        local~call, getbox, setbox = luatexbase.call_callback, tex.getbox, tex.setbox~
+        lua.get_functions_table()[\the \@@_finalize_box:] = function()
+          local~result = call('pre_shipout_filter', getbox(\the \l_shipout_box))
+          if~not (result == true) then~
+            setbox(\the \l_shipout_box, result~or~nil)
+          end~
+        end
+      }
+    }
+    \protected \luadef \@@_finalize_box: \the \@@_finalize_box:
+  } {
+    \cs_set_eq:NN \@@_finalize_box: \scan_stop:
+  }
+%    \end{macrocode}
+%  \end{macro}
 %
 %
 %  \begin{macro}{\@@_execute:}
@@ -618,7 +775,8 @@
 %
 %  \begin{macro}{\l_@@_group_level_tl}
 %    Helper token list to record the group level at which
-%    \cs{@@_execute:} is encountered.  \begin{macrocode}
+%    \cs{@@_execute:} is encountered.
+%    \begin{macrocode}
 \tl_new:N \l_@@_group_level_tl
 %    \end{macrocode}
 %  \end{macro}
@@ -632,28 +790,78 @@
 \cs_new:Npn \@@_execute_test_level: {
   \int_compare:nNnT
      \l_@@_group_level_tl < \tex_currentgrouplevel:D 
-     \tex_aftergroup:D
-  \@@_execute_cont:
+     \tex_aftergroup:D \@@_execute_cont:
 }
 %    \end{macrocode}
 %  \end{macro}
 %
 %
 %  \begin{macro}{\@@_execute_cont:}
+%    This does the actual shipout running several hooks as part of it.
+%    The code for them is passed as argument \verb=#2= to \verb=#4=
+%    to \cs{@@_execute_main_cont:Nnnn}; the first argument is the box
+%    to be shipped out.
+%    \begin{macrocode}
+\cs_new:Npn \@@_execute_cont: {
+  \@@_execute_main_cont:Nnnn
+     \l_shipout_box
+     { \hook_use:n {shipout/before} }
+     { \hook_if_empty:nF {shipout/foreground}
+         { \@@_add_foreground_picture:n
+             { \hook_use:n {shipout/foreground} } }
+%    \end{macrocode}
+%    If the user hook for the background (\hook{shipout/background}) has
+%    no code, there might still code in the kernel hook so we need to
+%    test for this too.
+%    We only test for the \cs{@kernel@before@shipout@background}
+%    though. If the  \cs{@kernel@after@shipout@background} needs
+%    executing even if the user hook is empty then we can add another
+%    test (or the kernel could put something into the before hook).
+%                   
+% \changes{v1.0d}{2020/11/23}{Check for both kernel and user hook (gh/431)}
+% \changes{v1.0f}{2021/01/08}{Added another kernel hook for more
+%    flexibility (cf \texttt{https://github.com/pgf-tikz/pgf/issues/960}}
+%    \begin{macrocode}
+       \bool_lazy_and:nnF
+         { \hook_if_empty_p:n {shipout/background} }
+         { \tl_if_empty_p:N \@kernel@before@shipout@background }
+         { \@@_add_background_picture:n
+           { \@kernel@before@shipout@background
+             \hook_use:n {shipout/background}
+             \@kernel@after@shipout@background }
+         }
+     }
+     { \hook_use:n {shipout/after} }
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\@@_execute_main_cont:Nnnn}
 %    When we have reached this point the shipout box has been
 %    processed and is available in \cs{l_shipout_box} and ready for
-%    real ship out (perhaps)..
+%    real ship out (unless it gets discarded during the process).
+%
+%    The three arguments hold hook code that is executed just before the
+%    actual shipout (\verb=#1=), within the shipout adding
+%    background and foreground material (\verb=#2=) and after the
+%    shipout has happened (\verb=#3=).
+%    These are passed as arguments because the same code without those
+%    hooks is also used when doing a ``raw'' shipout implemented by
+%    \cs{RawShipout}.
+%    The only hook that is always executed is that for the very last
+%    page, i.e., \hook{shipout/lastpage}.
 %
 %    First we quickly check if it is void (can't happen in the
 %    standard \LaTeX{} output routine but \cs{shipout} might be called
 %    from a package that has some special processing logic). If it is
 %    void we aren't shipping anything out and processing ends.\footnote{In that
-%    case we don't reset the deadcyles, that would be up to the OR
+%    case we don't reset the deadcycles, that would be up to the OR
 %    processing logic to do.}
 %    \begin{macrocode}
-\cs_new:Npn \@@_execute_cont: {
-  \box_if_empty:NTF \l_shipout_box
-    { \PackageWarning{ltshipout}{Ignoring~ void~ shipout~ box} }
+\cs_new:Npn \@@_execute_main_cont:Nnnn #1#2#3#4 {
+  \box_if_empty:NTF #1
+    { \@latex@warning{Ignoring~ void~ shipout~ box} }
     {
 %    \end{macrocode}
 %    Otherwise we assume that we will ship something and prepare for
@@ -661,7 +869,8 @@
 %    \cs{protect} while we are running the hook code).
 %    We also save the current \cs{protect} state to restore it later.
 %    \begin{macrocode}
-      \bool_gset_false:N \g_@@_discard_bool
+%      \bool_gset_false:N \g_@@_discard_bool  % setting this would disable
+                                              % \DiscardShipoutBox on doc-level
       \cs_set_eq:NN \@@_saved_protect: \protect
       \set@typeset@protect
 %    \end{macrocode}
@@ -670,11 +879,12 @@
 %    necessary as the code could access them via \cs{box_ht:N}, etc.,
 %    but it is perhaps convenient.}
 %    \begin{macrocode}
-      \@@_get_box_size:N \l_shipout_box
+      \@@_get_box_size:N #1
 %    \end{macrocode}
-%    Then we execute the \hook{shipout/before} hook.
+%    Then we execute the \hook{shipout/before} hook (or nothing in
+%    case of \cs{RawShipout}).
 %    \begin{macrocode}
-      \hook_use:n {shipout/before}
+      #2
 %    \end{macrocode}
 %    In \cs{g_shipout_totalpages_int} we count all shipout attempts so
 %    we increment that counter already here (the other one is
@@ -693,7 +903,7 @@
 %    we now test for it.
 %    \begin{macrocode}
       \bool_if:NTF \g_@@_discard_bool
-        { \PackageInfo{ltshipout}{Completed~ page~ discarded}
+        { \@latex@info@no@line{Completed~ page~ discarded}
           \bool_gset_false:N \g_@@_discard_bool
 %    \end{macrocode}
 %    As we are discarding the page box and not shipping anything out,
@@ -707,7 +917,7 @@
 %    needed? Or the resetting of \cs{protect} to its kernel value?}
 %    \begin{macrocode}
 %          \group_begin:
-%            \box_set_eq_drop:NN \l_shipout_box \l_shipout_box
+%            \box_set_eq_drop:NN #1 #1
 %          \group_end:
 %          \cs_set_eq:NN \protect \exp_not:N
         }
@@ -718,8 +928,8 @@
 %    once more but this time make it a warning, because the best
 %    practice way is to use the request mechanism.
 %    \begin{macrocode}
-        { \box_if_empty:NTF \l_shipout_box
-            { \PackageWarning{ltshipout}{
+        { \box_if_empty:NTF #1
+            { \@latex@warning{
                 Shipout~ box~ was~ voided~ by~ hook,\MessageBreak
                 ignoring~ shipout~ box  }
             }
@@ -743,33 +953,36 @@
 %    changed) and then look at the hooks \hook{shipout/foreground}
 %    and \hook{shipout/background}. If either or both are non-empty
 %    we add a \texttt{picture} environment to the box (in the
-%    foreground and or in the background) and execute the hook code
+%    foreground and/or in the background) and execute the hook code
 %    inside that environment.
 %    
 %    \begin{macrocode}
-              \@@_get_box_size:N \l_shipout_box
-              \hook_if_empty:nF {shipout/foreground}
-                   { \@@_add_foreground_picture:n
-                     { \hook_use:n {shipout/foreground} } }
+              \@@_get_box_size:N #1
 %    \end{macrocode}
-%    If there is no user hook, there might still code in the kernel hook.
-% \changes{v1.0d}{2020/11/23}{Check for both kernel and user hook (gh/431)}
+%    The first hook we run is the \hook{shipout/firstpage} hook. This
+%    is only done once, then the \cs{@@_run_firstpage_hook:}
+%    command redefines itself to do nothing. If the hook contains
+%    \cs{special}s for integration at the top of the page they will be
+%    temporarily stored in a safe place and added later with
+%    \cs{@@_add_firstpage_specials:}.
+%    \begin{macrocode}
+              \@@_run_firstpage_hook:
+%    \end{macrocode}
+%    Run the hooks for background and foreground or, if this
+%    is called by \cs{RawShipout}, copy the box \cs{l_@@_raw_box} to
+%    \cs{l_shipout_box} so that firstpage and lastpage material gets
+%    added if necessary (that is always done to \cs{l_shipout_box}.
 %    \begin{macrocode}
-              \bool_lazy_and:nnF
-                   { \hook_if_empty_p:n {shipout/background} }
-                   { \tl_if_empty_p:N \@kernel@before@shipout@background }
-                   { \@@_add_background_picture:n
-                     { \@kernel@before@shipout@background
-                       \hook_use:n {shipout/background} } }
+              #3
 %    \end{macrocode}
-%    We then run \cs{@@_execute_firstpage_hook:} that adds
+%    We then run \cs{@@_add_firstpage_specials:} that adds
 %    the content of the hook \hook{shipout/firstpage} to the
 %    start of the first page (if non-empty). It is then redefined to
 %    do nothing on later pages.
 %    \begin{macrocode}
-              \@@_execute_firstpage_hook:
+              \@@_add_firstpage_specials:
 %    \end{macrocode}
-%    The we check if we have to add the \hook{shipout/lastpage} hook
+%    Then we check if we have to add the \hook{shipout/lastpage} hook
 %    or the corresponding kernel hook
 %    because we have reached the last page. This test will be false for
 %    all but one (and hopefully the correct) page.
@@ -780,12 +993,14 @@
                     { \hook_if_empty_p:n {shipout/lastpage} }
                     { \tl_if_empty_p:N \@kernel@after@shipout@lastpage }
                     { \@@_debug:n { \typeout{Executing~ lastpage~ hook~
-                          on~ page~ \int_use:N \g_shipout_readonly_int }        }
-                      \_@@_add_foreground_box:n { \UseHook{shipout/lastpage}
-                                                  \@kernel@after@shipout@lastpage }
+                          on~ page~ \int_use:N \g_shipout_readonly_int } }
+                      \_@@_add_foreground_box:n
+                          { \UseHook{shipout/lastpage}
+                            \@kernel@after@shipout@lastpage }
                     }
                     \bool_gset_true:N \g_@@_lastpage_handled_bool
                 }
+              \@@_finalize_box:
 %    \end{macrocode}
 %    Finally we run the actual \TeX{} primitive for shipout. As that will
 %    expand delayed \cs{write} statements inside the page in which
@@ -794,6 +1009,21 @@
 %    \begin{macrocode}
               \cs_set_eq:NN \protect \exp_not:N
               \tex_shipout:D \box_use:N \l_shipout_box
+%    \end{macrocode}
+%    The \cs{l_shipout_box} may contain the firstpage material if this
+%    was the very first shipout. That makes it unsuitable for reuse in
+%    another shipout, so as a safety measure the next command resets
+%    \cs{l_shipout_box} to its earlier state if that is necessary. On
+%    later pages this is then a no-op.
+%    \begin{macrocode}
+              \@@_drop_firstpage_specials:
+%    \end{macrocode}
+%    The \hook{shipout/after} hook (if in \verb=#4=) needs to run with
+%    \cs{protect}ed commands again being executed, because that hook
+%    will ``typeset'' material added at the top of the next page.
+%    \begin{macrocode}
+              \set@typeset@protect
+              #4
             }
         }
 %    \end{macrocode}
@@ -808,6 +1038,54 @@
 %  \end{macro}
 %
 %
+%
+%
+%  \begin{macro}{\@@_execute_raw:,
+%                \@@_execute_test_level_raw:}
+%
+%    This implements the ``raw'' shipout which bypasses the before,
+%    foreground, background and after hooks. It follows the same pattern than
+%    \cs{_@@_execute_raw:} except that it finally calls
+%    \cs{_@@_execute_main_cont:Nnnn} with three empty arguments.
+%    instead of the hook code.
+%    \begin{macrocode}
+\cs_set_protected:Npn \@@_execute_raw: {
+  \tl_set:Nx \l_@@_group_level_tl
+     { \int_value:w \tex_currentgrouplevel:D }
+  \tex_afterassignment:D \@@_execute_test_level_raw:
+  \tex_setbox:D \l_@@_raw_box
+}
+%    \end{macrocode}
+%    
+%    \begin{macrocode}
+\cs_new:Npn \@@_execute_test_level_raw: {
+  \int_compare:nNnT
+     \l_@@_group_level_tl < \tex_currentgrouplevel:D
+     \tex_aftergroup:D \@@_execute_nohooks_cont:
+}
+%    \end{macrocode}
+%    Well, not totally empty arguments, we add some debugging if we
+%    are actually doing a shipout.
+%    \begin{macrocode}
+\cs_new:Npn \@@_execute_nohooks_cont: {
+  \@@_execute_main_cont:Nnnn \l_@@_raw_box
+     {} { \@@_debug:n{ \typeout{Doing~ raw~ shipout~ ...} }
+          \box_set_eq:NN \l_shipout_box \l_@@_raw_box } {} 
+} 
+%    \end{macrocode}
+%  \end{macro}
+
+%  \begin{macro}{\RawShipout}
+%    The interface name for raw shipout.
+% \changes{v1.0g}{2021/01/10}{Macro added}
+%    \begin{macrocode}
+\cs_gset_eq:NN \RawShipout \@@_execute_raw:
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%
 %  \begin{macro}{\@@_saved_protect:}
 %    Remember the current \cs{protect} state.
 %    \begin{macrocode}
@@ -815,13 +1093,14 @@
 %    \end{macrocode}
 %  \end{macro}
 %
-%  \begin{macro}{shipout/before,
+%  \begin{macro}{shipout/before,shipout/after,
 %                   shipout/foreground,shipout/background,
 %                   shipout/firstpage,
 %                   shipout/lastpage}
 %    Declaring all hooks for the shipout code.
 %    \begin{macrocode}
 \hook_new:n{shipout/before}
+\hook_new:n{shipout/after}
 \hook_new:n{shipout/foreground}
 \hook_new:n{shipout/background}
 \hook_new:n{shipout/firstpage}
@@ -832,36 +1111,71 @@
 %
 %
 %  \begin{macro}{\@kernel@after@shipout@lastpage,
-%                \@kernel@before@shipout@background}
+%                \@kernel@before@shipout@background,
+%                \@kernel@after@shipout@background}
 %    And here are the internal kernel hooks going before or after the
 %    public ones where needed.
+% \changes{v1.0g}{2021/01/10}{Internal hook
+%                             \cs{@kernel@after@shipout@background} added}
 %    \begin{macrocode}
 \let\@kernel@after@shipout@lastpage\@empty
 \let\@kernel@before@shipout@background\@empty
+\let\@kernel@after@shipout@background\@empty
 %    \end{macrocode}
 %  \end{macro}
 %
 %
-%  \begin{macro}{\@@_execute_firstpage_hook: }
-%    This command adds any specials into a box and adds that to the
-%    very beginning of the first box shipped out. After that we
-%    redefine it to do nothing on later pages.
+%  \begin{macro}{\@@_run_firstpage_hook:}
+%
+% \changes{v1.0h}{2021/01/19}{Handling of firstpage hook altered}
+%
+%    There are three commands to handle the \hook{shipout/firstpage}
+%    hook:
+%    \cs{@@_run_firstpage_hook:}, \cs{@@_add_firstpage_specials:} and
+%    \cs{@@_drop_firstpage_specials:}. 
+%
+%    That hook is supposed to contain \cs{special}s and similar
+%    material to be placed at the very beginning of the output page
+%    and so it needs careful placing to avoid that anything else gets
+%    in front of it. And this means we have to wait with this until
+%    other hooks such as \hook{shipout/background} have added their
+%    bits. It is also important that such \cs{special}s show up only
+%    on the very first page, so if this page gets saved before
+%    \cs{shipout} for later reuse, we have to make sure that they
+%    aren't in the saved version.
+%
+%    In addition the hook may also contain code to be executed ``first'', e.g.,
+%    visible from code in \hook{shipout/background} and this conflicts
+%    with adding the \cs{special}s late.
+%
+%    Therefore the processing is split into different parts:
+%    \cs{@@_run_firstpage_hook:} is done early and checks if there is
+%    any material in the hook. 
 %    \begin{macrocode}
-\cs_new:Npn \@@_execute_firstpage_hook: {
+\cs_new:Npn \@@_run_firstpage_hook: {
+  \hook_if_empty:nTF {shipout/firstpage}
 %    \end{macrocode}
-%    Adding something to the beginning means adding it to the
-%    background as that  layer is done first in the output. Of course
-%    that is only needed if the hook actually contains anything.
+%    If not then we define the other two commands to do nothing.
 %    \begin{macrocode}
-  \hook_if_empty:nF {shipout/firstpage}
-       { \@@_add_background_box:n { \UseHook{shipout/firstpage} } }
+       {
+         \cs_gset_eq:NN \@@_add_firstpage_specials:  \prg_do_nothing:
+         \cs_gset_eq:NN \@@_drop_firstpage_specials: \prg_do_nothing:
+       }
+%    \end{macrocode}
+%    If there is material we execute inside a box, which means any
+%    \cs{special} will end up in that box and any other code is
+%    executed and can have side effects (as long as they are global).
+%    \begin{macrocode}
+       {
+         \hbox_set:Nn \l_@@_firstpage_box { \UseHook{shipout/firstpage} }
+       }
 %    \end{macrocode}
 %    Once we are here we change the definition to do nothing next time
 %    and we also change the command used to implement \cs{AtBeginDvi}
-%    to become a warning and not  add further material to a hook that
+%    to become a warning and not add further material to a hook that
 %    is never used again.
 %    \begin{macrocode}
-  \cs_gset_eq:NN \@@_execute_firstpage_hook: \prg_do_nothing:
+  \cs_gset_eq:NN \@@_run_firstpage_hook: \prg_do_nothing:
   \cs_gset:Npn \@@_add_firstpage_material:Nn ##1 ##2 {
     \@latex@warning{
         First~ page~ is~ already~ shipped~ out,~ ignoring\MessageBreak
@@ -869,8 +1183,67 @@
   }
 }
 %    \end{macrocode}
+% \end{macro}
+%
+%
+%
+%  \begin{macro}{\@@_add_firstpage_specials:,\@@_drop_firstpage_specials:}
+%    The \cs{@@_add_firstpage_specials:} then adds the \cs{special}s
+%    stored in \cs{l_@@_firstpage_box} to the page to be shipped out
+%    when the time is ready. Note that if there was no material in the
+%    \hook{shipout/firstpage} hook then this command gets redefined to
+%    do nothing. But for most documents there is something, e.g., some
+%    PostScript header, or some meta data declaration, etc.\ so by 
+%    default we assume there is something to do.
+%    \begin{macrocode}
+\cs_new:Npn \@@_add_firstpage_specials: {
+%    \end{macrocode}
+%    First we make a copy of the \cs{l_shipout_box} that we can
+%    restore it later on.
+%    \begin{macrocode}
+  \box_set_eq:NN \l_@@_raw_box \l_shipout_box
+%    \end{macrocode}
+%    Adding something to the beginning means adding it to the
+%    background as that layer is done first in the output. 
+%    \begin{macrocode}
+  \@@_add_background_box:n { \hbox_unpack_drop:N \l_@@_firstpage_box }
+%    \end{macrocode}
+%    After the actual shipout \cs{@@_drop_firstpage_specials:} is
+%    run to
+%    restore the earlier content of \cs{l_shipout_box} and then
+%    redefines itself again to do nothing.
+%
+%    As a final act we change the definition to do nothing next time.
+%    \begin{macrocode}
+  \cs_gset_eq:NN \@@_add_firstpage_specials: \prg_do_nothing:
+}
+%    \end{macrocode}
+%
+%    The \cs{@@_drop_firstpage_specials:} is run after the shipout has
+%    occurred but before the \hook{shipout/afterpage} hook is executed.
+%    That is the point where we have to restore the \cs{ShipoutBox} to
+%    its state without the \hook{shipout/firstpage} material.
+%    \begin{macrocode}
+\cs_new:Npn \@@_drop_firstpage_specials: {
+    \box_set_eq:NN \l_shipout_box \l_@@_raw_box
+%    \end{macrocode}
+%    If there was no such material then \cs{@@_run_firstpage_hook:}
+%    will have changed the definition to a no-op already. Otherwise
+%    this is what we do here.
+%    \begin{macrocode}
+    \cs_gset_eq:NN \@@_drop_firstpage_specials:  \prg_do_nothing:
+  }
+%    \end{macrocode}
 %  \end{macro}
 %
+
+%  \begin{macro}{\l_@@_firstpage_box}
+%    The box to hold any firstpage \cs{special}s.
+%    \begin{macrocode}
+\box_new:N \l_@@_firstpage_box
+%    \end{macrocode}
+%  \end{macro}
+
 %
 %  \begin{macro}{\g_@@_lastpage_handled_bool}
 %    A boolean to signal if we have already handled the
@@ -911,8 +1284,8 @@
   \dim_set:Nn \l_shipout_box_ht_dim { \box_ht:N #1 }
   \dim_set:Nn \l_shipout_box_dp_dim { \box_dp:N #1 }
   \dim_set:Nn \l_shipout_box_wd_dim { \box_wd:N #1 }
-  \dim_set:Nn \l_shipout_box_ht_plus_dp_dim { \l_shipout_box_ht_dim +
-                                         \l_shipout_box_dp_dim }
+  \dim_set:Nn \l_shipout_box_ht_plus_dp_dim
+      { \l_shipout_box_ht_dim + \l_shipout_box_dp_dim }
 }
 %    \end{macrocode}
 %  \end{macro}
@@ -1442,7 +1815,8 @@
 %    defined so we better not use \cs{cs_new_protected:Npn} here.
 % \changes{v1.0d}{2020/11/24}{Support for roll forward (gh/434)}
 %    \begin{macrocode}
-\cs_set_protected:Npn \AtBeginDvi {\@@_add_firstpage_material:Nn \AtBeginDvi}
+\cs_set_protected:Npn \AtBeginDvi
+                      {\@@_add_firstpage_material:Nn \AtBeginDvi}
 %    \end{macrocode}
 %  \end{macro}
 %
@@ -1471,6 +1845,7 @@
 %                \@expl@@@shipout@add@foreground@picture@@n}
 %    Some internals needed elsewhere.
 %
+%  \InternalDetectionOff
 %    \begin{macrocode}
 \cs_set_eq:NN \@expl@@@shipout@add@firstpage@material@@Nn
               \__shipout_add_firstpage_material:Nn
@@ -1495,6 +1870,7 @@
 \cs_set_eq:NN \@expl@@@shipout@add@foreground@picture@@n
               \__shipout_add_foreground_picture:n
 %    \end{macrocode}
+%  \InternalDetectionOn
 %  \end{macro}
 %
 %    \begin{macrocode}
@@ -1524,6 +1900,7 @@
 %<latexrelease>                \csname tex_shipout:D\endcsname
 %<latexrelease>\fi
 %<latexrelease>
+%<latexrelease>\let \RawShipout\@undefined
 %<latexrelease>\let \ShipoutBox\@undefined
 %<latexrelease>\let \ReadonlyShipoutCounter \@undefined
 %<latexrelease>\let \c@totalpages \@undefined
@@ -1547,23 +1924,13 @@
 %<latexrelease>\let \ShipoutBoxDepth \@undefined
 %<latexrelease>\let \ShipoutBoxWidth \@undefined
 %<latexrelease>
-%<latexrelease>\let \AtBeginShipoutDiscard \@undefined
-%<latexrelease>
-%<latexrelease>\let \AtBeginShipoutAddToBox \@undefined
-%<latexrelease>\let \AtBeginShipoutAddToBoxForeground \@undefined
-%<latexrelease>\let \AtBeginShipoutUpperLeft \@undefined
-%<latexrelease>\let \AtBeginShipoutUpperLeftForeground \@undefined
-%<latexrelease>
 %    \end{macrocode}
 %    We do not undo a substitution when rolling back. As the file
 %    support gets undone the underlying data is no longer used (and
 %    sufficiently obscure that it should not interfere with existing
 %    commands) and properly removing it would mean we need to make the
-%    \cs{unclare@...} and its support macros available in all earlier
+%    \cs{undeclare@...} and its support macros available in all earlier
 %    kernel releases which is pointless (and actually worse).
-%    \begin{macrocode}
-%\undeclare@file@substitution{everyshi.sty}
-%    \end{macrocode}
 %    
 %    \begin{macrocode}
 %<latexrelease>
@@ -1647,7 +2014,7 @@
 %    \begin{macrocode}
 %<*atbegshi-ltx>
 \ProvidesPackage{atbegshi-ltx}
-   [2020/10/15 v1.0b
+   [2021/01/10 v1.0c
      Emulation of the original atbegshi^^Jpackage with kernel methods]
 %    \end{macrocode}
 %
@@ -1659,6 +2026,7 @@
 %  \end{macro}
 %
 %
+%
 %  \begin{macro}{\AtBeginShipoutInit}
 %    Compatibility only, we aren't delaying \ldots
 %    \begin{macrocode}
@@ -1712,6 +2080,19 @@
 %    \end{macrocode}
 %  \end{macro}
 %
+%  \begin{macro}{\AtBeginShipoutOriginalShipout}
+%    This offers the raw \cs{shipout} primitive of the engine. A page
+%    shipped out with this is not counted by
+%    \cs{ReadonlyShipoutCounter} counter and thus the mechanism to
+%    place \cs{special}s at the very end of the output might fail,
+%    etc. It should therefore not be used in new applications but is
+%    only provided to allow  running legacy code. For new code use the
+%    commands provided by the kernel instead.
+%    \begin{macrocode}
+\ExplSyntaxOn
+\cs_new_eq:NN \AtBeginShipoutOriginalShipout \tex_shipout:D
+%    \end{macrocode}
+%  \end{macro}
 %
 %
 %  \begin{macro}{\ShipoutBoxHeight,\ShipoutBoxWidth,\ShipoutBoxDepth}
@@ -1720,7 +2101,6 @@
 %    \verb=\the\ht<box>= value. This may has some implications in some
 %    use cases and if that is a problem then it might need changing.
 %    \begin{macrocode}
-\ExplSyntaxOn  
 \cs_new:Npn \ShipoutBoxHeight { \dim_use:N \l_shipout_box_ht_dim }
 \cs_new:Npn \ShipoutBoxDepth  { \dim_use:N \l_shipout_box_dp_dim }
 \cs_new:Npn \ShipoutBoxWidth  { \dim_use:N \l_shipout_box_wd_dim }
@@ -1747,56 +2127,8 @@
 %
 % \subsection{Package \pkg{everyshi} emulation}
 %
-%    \begin{macrocode}
-%<*everyshi-ltx>
-%    \end{macrocode}
-%
-%    \begin{macrocode}
-\ProvidesPackage{everyshi-ltx}
-   [2020/10/15 v1.0b
-    Emulation of the original everyshi^^Jpackage with kernel methods]
-%    \end{macrocode}
-%    
-%  \begin{macro}{\EveryShipout,\AtNextShipout}
-%    This package has only two public commands so simulating it is easy:
-%    \begin{macrocode}
-\protected \def \EveryShipout  {\AddToHook{shipout/before}}
-\protected \def \AtNextShipout {\AddToHookNext{shipout/before}}
-%    \end{macrocode}
-%  \end{macro}
-%
-%    \begin{macrocode}
-%    This is one difference between \pkg{everyshi} and the kernel
-%    implementation, the latter does not directly use box 255.
-%
-%    For usage by ordinary users this makes no difference but of a
-%    package use complicated code together with \pkg{everyshi} and
-%    directly manipulates box 255 then this package needs updating.
-%    In most cases the updates are simple because the kernel offers
-%    hooks that makes such complicated code unnecessary.
-%
-%    We therefore add a little file into the adjusted package
-%    \begin{macrocode}
-%%
-%%   In normal circumstances the above emulation is sufficient and in
-%%   all known packages (we know of) that use everyshi it either works or
-%%   the packages have been adjusted. 
-%%
-%%   Code that directly manipulates box 255, however, might fail. 
-%%   If that is the case look at the shipout hooks offered now as
-%%   they are normally sufficient to avoid such manipulations (or
-%%   replace box 255 with \ShipoutBox in the code.
-%%
-%</everyshi-ltx>
-%    \end{macrocode}
-%
-%
-%    If the package is requested we substitute the one above:
-%    \begin{macrocode}
-%<*2ekernel>
-\declare@file@substitution{everyshi.sty}{everyshi-ltx.sty}
-%</2ekernel>
-%    \end{macrocode}
+%    This is now directly handled in that package so emulation is not
+%    necessary any more.
 %
 %
 %    Rather important :-)
diff --git a/Master/texmf-dist/source/latex-dev/base/ltspace.dtx b/Master/texmf-dist/source/latex-dev/base/ltspace.dtx
index 8b933e8c971..17fb0d65185 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltspace.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltspace.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/lttab.dtx b/Master/texmf-dist/source/latex-dev/base/lttab.dtx
index 545b30d3af1..a964b365753 100644
--- a/Master/texmf-dist/source/latex-dev/base/lttab.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/lttab.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/lttextcomp.dtx b/Master/texmf-dist/source/latex-dev/base/lttextcomp.dtx
index 3ea90d005f9..d840f0448b9 100644
--- a/Master/texmf-dist/source/latex-dev/base/lttextcomp.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/lttextcomp.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 2019-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -26,6 +26,9 @@
 % extension .ins) which are part of the distribution.
 %
 % \fi
+%
+%%% From File: lttextcomp.dtx
+%
 % \iffalse
 %
 %<*driver>
@@ -33,7 +36,7 @@
 %
 %
 \ProvidesFile{lttextcomp.dtx}
-             [2020/12/05 v1.0d LaTeX Kernel (text companion symbols)]
+             [2021/01/20 v1.0d LaTeX Kernel (text companion symbols)]
 % \iffalse
 \documentclass{ltxdoc}
 \begin{document}
@@ -362,13 +365,14 @@
 }
 %    \end{macrocode}
 %  \end{macro}
-
-
-
-
+%
+%
+%
+%
+%
 % \begin{macro}{\tc@fake@euro}
 %    |\tc@fake@euro|  is an example of a ``fake'' definition to use in  arg |#3| of
-%    |\CheckEncodingSubset| when a symbol is not available in a
+%    the command |\CheckEncodingSubset| when a symbol is not available in a
 %    certain font family. Here we produce a poor man's Euro symbol by combining
 %    a ``C'' with a ``=''.
 %    \begin{macrocode}
@@ -386,10 +390,10 @@
 }
 %    \end{macrocode}
 % \end{macro}
-
-
-
-
+%
+%
+%
+%
 % \begin{macro}{\tc@check@symbol}
 % \begin{macro}{\tc@check@accent}
 %    These are two abbreviations that we use below to check symbols
@@ -401,12 +405,12 @@
 %    to ensure that |\textcurrency| is only typeset if the current
 %    font has a \texttt{TS1} subset id of less than 3. Otherwise
 %    |\tc@error| is called telling the user that for this font family
-%    |\textcurreny| is not available.
+%    |\textcurrency| is not available.
 %    \begin{macrocode}
 \def\tc@check@symbol{\CheckEncodingSubset\UseTextSymbol{TS1}\tc@subst}
 %    \end{macrocode}
 %
-%    Accents and been mad an error in the \texttt{textcomp} package when
+%    Accents have been made an error in the \texttt{textcomp} package when
 %    not available. Now that we provide the functionality in the
 %    kernel we avoid the error by swapping in a \texttt{T1} accent if
 %    the \texttt{TS1} accent is not available.
@@ -415,7 +419,8 @@
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\def\tc@check@accent#1{\CheckEncodingSubset\UseTextAccent{TS1}{\tc@swap@accent#1}}
+\def\tc@check@accent#1{\CheckEncodingSubset\UseTextAccent
+                                           {TS1}{\tc@swap@accent#1}}
 \def\tc@swap@accent#1#2{\UseTextAccent{T1}#1}
 %    \end{macrocode}
 % \end{macro}
@@ -430,17 +435,17 @@
 %
 %    \begin{macrocode}
 \DeclareTextSymbolDefault{\textdollar}{TS1}
-\UndeclareTextCommand{\textdollar}  {OT1}         % don't use the OT1 def any longer
+\UndeclareTextCommand{\textdollar}{OT1}  % don't use the OT1 def any longer
 %    \end{macrocode}
 %
 %    \begin{macrocode}
 \DeclareTextSymbolDefault{\textsterling}{TS1}
-\UndeclareTextCommand{\textsterling}{OT1}         % don't use the OT1 def any longer
+\UndeclareTextCommand{\textsterling}{OT1}% don't use the OT1 def any longer
 %    \end{macrocode}
 %
 %    \begin{macrocode}
 \DeclareTextSymbolDefault{\textperthousand}{TS1}
-\UndeclareTextCommand{\textperthousand}{T1}       % don't use the T1 def
+\UndeclareTextCommand{\textperthousand}{T1} % don't use the T1 def
 %    \end{macrocode}
 %    Using \cs{UndeclareTextCommand} above is enough only if the
 %    encoding definition files are not reloaded afterwards. In the
@@ -462,9 +467,9 @@
 %    \end{macrocode}
 %
 %    And here are the other \texttt{TS1} glyphs that are implemented
-%    by every font (or nearly everyone---a few are commented out and
+%    by every font (or nearly every---a few are commented out and
 %    moved to sub-encoding 9,
-%    because they aren't around in one or two fonts.
+%    because they aren't around in some fonts.
 %    \begin{macrocode}
 %%\DeclareTextSymbolDefault{\textbardbl}{TS1} % subst in sub-enc 9 above
 \DeclareTextSymbolDefault{\textbrokenbar}{TS1}
@@ -541,31 +546,49 @@
 %
 %    \begin{macrocode}
 \ifx\Umathcode\@undefined
-  \DeclareTextCommandDefault{\capitalacute}       {\tc@check@accent{\'}2\capitalacute}
-  \DeclareTextCommandDefault{\capitalbreve}       {\tc@check@accent{\u}2\capitalbreve}
-  \DeclareTextCommandDefault{\capitalcaron}       {\tc@check@accent{\v}2\capitalcaron}
-  \DeclareTextCommandDefault{\capitalcedilla}     {\tc@check@accent{\c}2\capitalcedilla}
-  \DeclareTextCommandDefault{\capitalcircumflex}  {\tc@check@accent{\^}2\capitalcircumflex}
-  \DeclareTextCommandDefault{\capitaldieresis}    {\tc@check@accent{\"}2\capitaldieresis}
-  \DeclareTextCommandDefault{\capitaldotaccent}   {\tc@check@accent{\.}2\capitaldotaccent}
-  \DeclareTextCommandDefault{\capitalgrave}       {\tc@check@accent{\`}2\capitalgrave}
-  \DeclareTextCommandDefault{\capitalhungarumlaut}{\tc@check@accent{\H}2\capitalhungarumlaut}
-  \DeclareTextCommandDefault{\capitalmacron}      {\tc@check@accent{\=}2\capitalmacron}
-  \DeclareTextCommandDefault{\capitalogonek}      {\tc@check@accent{\k}2\capitalogonek}
-  \DeclareTextCommandDefault{\capitalring}        {\tc@check@accent{\r}2\capitalring}
-  \DeclareTextCommandDefault{\capitaltie}         {\tc@check@accent{\t}2\capitaltie}
-  \DeclareTextCommandDefault{\capitaltilde}       {\tc@check@accent{\~}2\capitaltilde}
+  \DeclareTextCommandDefault{\capitalacute}
+                            {\tc@check@accent{\'}2\capitalacute}
+  \DeclareTextCommandDefault{\capitalbreve}
+                            {\tc@check@accent{\u}2\capitalbreve}
+  \DeclareTextCommandDefault{\capitalcaron}
+                            {\tc@check@accent{\v}2\capitalcaron}
+  \DeclareTextCommandDefault{\capitalcedilla}
+                            {\tc@check@accent{\c}2\capitalcedilla}
+  \DeclareTextCommandDefault{\capitalcircumflex}
+                            {\tc@check@accent{\^}2\capitalcircumflex}
+  \DeclareTextCommandDefault{\capitaldieresis}
+                            {\tc@check@accent{\"}2\capitaldieresis}
+  \DeclareTextCommandDefault{\capitaldotaccent}
+                            {\tc@check@accent{\.}2\capitaldotaccent}
+  \DeclareTextCommandDefault{\capitalgrave}
+                            {\tc@check@accent{\`}2\capitalgrave}
+  \DeclareTextCommandDefault{\capitalhungarumlaut}
+                            {\tc@check@accent{\H}2\capitalhungarumlaut}
+  \DeclareTextCommandDefault{\capitalmacron}
+                            {\tc@check@accent{\=}2\capitalmacron}
+  \DeclareTextCommandDefault{\capitalogonek}
+                            {\tc@check@accent{\k}2\capitalogonek}
+  \DeclareTextCommandDefault{\capitalring}
+                            {\tc@check@accent{\r}2\capitalring}
+  \DeclareTextCommandDefault{\capitaltie}
+                            {\tc@check@accent{\t}2\capitaltie}
+  \DeclareTextCommandDefault{\capitaltilde}
+                            {\tc@check@accent{\~}2\capitaltilde}
 %    \end{macrocode}
 %    For \cs{newtie} and \cs{capitalnewtie} this is actually wrong, they should pick up
 %    the accent from the substitution font (not done yet).
 %    \begin{macrocode}
-  \DeclareTextCommandDefault{\newtie}             {\tc@check@accent{\t}2\newtie}
-  \DeclareTextCommandDefault{\capitalnewtie}      {\tc@check@accent{\t}2\capitalnewtie}
+  \DeclareTextCommandDefault{\newtie}
+                            {\tc@check@accent{\t}2\newtie}
+  \DeclareTextCommandDefault{\capitalnewtie}
+                            {\tc@check@accent{\t}2\capitalnewtie}
 %    \end{macrocode}
 %
 %    In Unicode engines we just execute the simple accents:
-% \changes{v1.0c}{2020/02/10}{Use \cs{@tabacckludge} for tabbing where necessary (gh/271)}
-% \changes{v1.0d}{2020/04/29}{Make all capital accents text commands for hyperref (gh/332)}
+% \changes{v1.0c}{2020/02/10}{Use \cs{@tabacckludge} for
+%      tabbing where necessary (gh/271)}
+% \changes{v1.0d}{2020/04/29}{Make all capital accents text
+%      commands for hyperref (gh/332)}
 %    \begin{macrocode}
 \else
   \DeclareTextCommandDefault\capitalacute{\@tabacckludge'}
@@ -593,8 +616,10 @@
 %    The next two symbols exist in some fonts (faked?), but we ignore
 %    that to keep the subsets reasonable compact and most important linear.
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textlbrackdbl}      {\tc@check@symbol2\textlbrackdbl}
-\DeclareTextCommandDefault{\textrbrackdbl}      {\tc@check@symbol2\textrbrackdbl}
+\DeclareTextCommandDefault{\textlbrackdbl}
+                          {\tc@check@symbol2\textlbrackdbl}
+\DeclareTextCommandDefault{\textrbrackdbl}
+                          {\tc@check@symbol2\textrbrackdbl}
 %    \end{macrocode}
 %
 %
@@ -603,72 +628,118 @@
 %    claim they aren't in sub-encoding 2 as that's true for most
 %    fonts.
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\texteightoldstyle}  {\tc@check@symbol2\texteightoldstyle}
-\DeclareTextCommandDefault{\textfiveoldstyle}   {\tc@check@symbol2\textfiveoldstyle}
-\DeclareTextCommandDefault{\textfouroldstyle}   {\tc@check@symbol2\textfouroldstyle}
-\DeclareTextCommandDefault{\textnineoldstyle}   {\tc@check@symbol2\textnineoldstyle}
-\DeclareTextCommandDefault{\textoneoldstyle}    {\tc@check@symbol2\textoneoldstyle}
-\DeclareTextCommandDefault{\textsevenoldstyle}  {\tc@check@symbol2\textsevenoldstyle}
-\DeclareTextCommandDefault{\textsixoldstyle}    {\tc@check@symbol2\textsixoldstyle}
-\DeclareTextCommandDefault{\textthreeoldstyle}  {\tc@check@symbol2\textthreeoldstyle}
-\DeclareTextCommandDefault{\texttwooldstyle}    {\tc@check@symbol2\texttwooldstyle}
-\DeclareTextCommandDefault{\textzerooldstyle}   {\tc@check@symbol2\textzerooldstyle}
-%    \end{macrocode}
-%
-%
-%
-%    The next set of glyphs is special to TeX fonts (and available
-%    with a few older PS fonts supported in the virtual fonts), but
+\DeclareTextCommandDefault{\texteightoldstyle}
+                          {\tc@check@symbol2\texteightoldstyle}
+\DeclareTextCommandDefault{\textfiveoldstyle}
+                          {\tc@check@symbol2\textfiveoldstyle}
+\DeclareTextCommandDefault{\textfouroldstyle}
+                          {\tc@check@symbol2\textfouroldstyle}
+\DeclareTextCommandDefault{\textnineoldstyle}
+                          {\tc@check@symbol2\textnineoldstyle}
+\DeclareTextCommandDefault{\textoneoldstyle}
+                          {\tc@check@symbol2\textoneoldstyle}
+\DeclareTextCommandDefault{\textsevenoldstyle}
+                          {\tc@check@symbol2\textsevenoldstyle}
+\DeclareTextCommandDefault{\textsixoldstyle}
+                          {\tc@check@symbol2\textsixoldstyle}
+\DeclareTextCommandDefault{\textthreeoldstyle}
+                          {\tc@check@symbol2\textthreeoldstyle}
+\DeclareTextCommandDefault{\texttwooldstyle}
+                          {\tc@check@symbol2\texttwooldstyle}
+\DeclareTextCommandDefault{\textzerooldstyle}
+                          {\tc@check@symbol2\textzerooldstyle}
+%    \end{macrocode}
+%
+%
+%
+%    The next set of glyphs is special to \TeX{} fonts (and available
+%    with a few older PS fonts supported through virtual fonts), but
 %    not any longer in the majority of fonts provided through
 %    autoinst, so we pretend there aren't available in sub-encoding 2
 %    and below.
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textacutedbl}       {\tc@check@symbol2\textacutedbl}
-\DeclareTextCommandDefault{\textasciiacute}     {\tc@check@symbol2\textasciiacute}
-\DeclareTextCommandDefault{\textasciibreve}     {\tc@check@symbol2\textasciibreve}
-\DeclareTextCommandDefault{\textasciicaron}     {\tc@check@symbol2\textasciicaron}
-\DeclareTextCommandDefault{\textasciidieresis}  {\tc@check@symbol2\textasciidieresis}
-\DeclareTextCommandDefault{\textasciigrave}     {\tc@check@symbol2\textasciigrave}
-\DeclareTextCommandDefault{\textasciimacron}    {\tc@check@symbol2\textasciimacron}
-\DeclareTextCommandDefault{\textgravedbl}       {\tc@check@symbol2\textgravedbl}
-\DeclareTextCommandDefault{\texttildelow}       {\tc@check@symbol2\texttildelow}
+\DeclareTextCommandDefault{\textacutedbl}
+                          {\tc@check@symbol2\textacutedbl}
+\DeclareTextCommandDefault{\textasciiacute}
+                          {\tc@check@symbol2\textasciiacute}
+\DeclareTextCommandDefault{\textasciibreve}
+                          {\tc@check@symbol2\textasciibreve}
+\DeclareTextCommandDefault{\textasciicaron}
+                          {\tc@check@symbol2\textasciicaron}
+\DeclareTextCommandDefault{\textasciidieresis}
+                          {\tc@check@symbol2\textasciidieresis}
+\DeclareTextCommandDefault{\textasciigrave}
+                          {\tc@check@symbol2\textasciigrave}
+\DeclareTextCommandDefault{\textasciimacron}
+                          {\tc@check@symbol2\textasciimacron}
+\DeclareTextCommandDefault{\textgravedbl}
+                          {\tc@check@symbol2\textgravedbl}
+\DeclareTextCommandDefault{\texttildelow}
+                          {\tc@check@symbol2\texttildelow}
 %    \end{macrocode}
 %
 %
 %    Finally those below are only available in CM-based fonts but in
 %    no font that has its origin outside of the \TeX{} world.
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textbaht}           {\tc@check@symbol2\textbaht}
-\DeclareTextCommandDefault{\textbigcircle}      {\tc@check@symbol2\textbigcircle}
-\DeclareTextCommandDefault{\textborn}           {\tc@check@symbol2\textborn}
-\DeclareTextCommandDefault{\textcentoldstyle}   {\tc@check@symbol2\textcentoldstyle}
-\DeclareTextCommandDefault{\textcircledP}       {\tc@check@symbol2\textcircledP}
-\DeclareTextCommandDefault{\textcopyleft}       {\tc@check@symbol2\textcopyleft}
-\DeclareTextCommandDefault{\textdblhyphenchar}  {\tc@check@symbol2\textdblhyphenchar}
-\DeclareTextCommandDefault{\textdblhyphen}      {\tc@check@symbol2\textdblhyphen}
-\DeclareTextCommandDefault{\textdied}           {\tc@check@symbol2\textdied}
-\DeclareTextCommandDefault{\textdiscount}       {\tc@check@symbol2\textdiscount}
-\DeclareTextCommandDefault{\textdivorced}       {\tc@check@symbol2\textdivorced}
-\DeclareTextCommandDefault{\textdollaroldstyle} {\tc@check@symbol2\textdollaroldstyle}
-\DeclareTextCommandDefault{\textguarani}        {\tc@check@symbol2\textguarani}
-\DeclareTextCommandDefault{\textleaf}           {\tc@check@symbol2\textleaf}
-\DeclareTextCommandDefault{\textlquill}         {\tc@check@symbol2\textlquill}
-\DeclareTextCommandDefault{\textmarried}        {\tc@check@symbol2\textmarried}
-\DeclareTextCommandDefault{\textmho}            {\tc@check@symbol2\textmho}
-\DeclareTextCommandDefault{\textmusicalnote}    {\tc@check@symbol2\textmusicalnote}
-\DeclareTextCommandDefault{\textnaira}          {\tc@check@symbol2\textnaira}
-\DeclareTextCommandDefault{\textopenbullet}     {\tc@check@symbol2\textopenbullet}
-\DeclareTextCommandDefault{\textpeso}           {\tc@check@symbol2\textpeso}
-\DeclareTextCommandDefault{\textpilcrow}        {\tc@check@symbol2\textpilcrow}
-\DeclareTextCommandDefault{\textrecipe}         {\tc@check@symbol2\textrecipe}
-\DeclareTextCommandDefault{\textreferencemark}  {\tc@check@symbol2\textreferencemark}
-\DeclareTextCommandDefault{\textrquill}         {\tc@check@symbol2\textrquill}
-\DeclareTextCommandDefault{\textservicemark}    {\tc@check@symbol2\textservicemark}
-\DeclareTextCommandDefault{\textsurd}           {\tc@check@symbol2\textsurd}
+\DeclareTextCommandDefault{\textbaht}
+                          {\tc@check@symbol2\textbaht}
+\DeclareTextCommandDefault{\textbigcircle}
+                          {\tc@check@symbol2\textbigcircle}
+\DeclareTextCommandDefault{\textborn}
+                          {\tc@check@symbol2\textborn}
+\DeclareTextCommandDefault{\textcentoldstyle}
+                          {\tc@check@symbol2\textcentoldstyle}
+\DeclareTextCommandDefault{\textcircledP}
+                          {\tc@check@symbol2\textcircledP}
+\DeclareTextCommandDefault{\textcopyleft}
+                          {\tc@check@symbol2\textcopyleft}
+\DeclareTextCommandDefault{\textdblhyphenchar}
+                          {\tc@check@symbol2\textdblhyphenchar}
+\DeclareTextCommandDefault{\textdblhyphen}
+                          {\tc@check@symbol2\textdblhyphen}
+\DeclareTextCommandDefault{\textdied}
+                          {\tc@check@symbol2\textdied}
+\DeclareTextCommandDefault{\textdiscount}
+                          {\tc@check@symbol2\textdiscount}
+\DeclareTextCommandDefault{\textdivorced}
+                          {\tc@check@symbol2\textdivorced}
+\DeclareTextCommandDefault{\textdollaroldstyle}
+                          {\tc@check@symbol2\textdollaroldstyle}
+\DeclareTextCommandDefault{\textguarani}
+                          {\tc@check@symbol2\textguarani}
+\DeclareTextCommandDefault{\textleaf}
+                          {\tc@check@symbol2\textleaf}
+\DeclareTextCommandDefault{\textlquill}
+                          {\tc@check@symbol2\textlquill}
+\DeclareTextCommandDefault{\textmarried}
+                          {\tc@check@symbol2\textmarried}
+\DeclareTextCommandDefault{\textmho}
+                          {\tc@check@symbol2\textmho}
+\DeclareTextCommandDefault{\textmusicalnote}
+                          {\tc@check@symbol2\textmusicalnote}
+\DeclareTextCommandDefault{\textnaira}
+                          {\tc@check@symbol2\textnaira}
+\DeclareTextCommandDefault{\textopenbullet}
+                          {\tc@check@symbol2\textopenbullet}
+\DeclareTextCommandDefault{\textpeso}
+                          {\tc@check@symbol2\textpeso}
+\DeclareTextCommandDefault{\textpilcrow}
+                          {\tc@check@symbol2\textpilcrow}
+\DeclareTextCommandDefault{\textrecipe}
+                          {\tc@check@symbol2\textrecipe}
+\DeclareTextCommandDefault{\textreferencemark}
+                          {\tc@check@symbol2\textreferencemark}
+\DeclareTextCommandDefault{\textrquill}
+                          {\tc@check@symbol2\textrquill}
+\DeclareTextCommandDefault{\textservicemark}
+                          {\tc@check@symbol2\textservicemark}
+\DeclareTextCommandDefault{\textsurd}
+                          {\tc@check@symbol2\textsurd}
 %    \end{macrocode}
 %
 %    The \cs{textpertenthousand} also belongs in this group but here
-%    we have a choice: in T1 there is definition for
+%    we have a choice: in T1 there is a definition for
 %    \cs{textpertenthousand} making the symbol up from \% and
 %    \verb=\char 24= (twice) but in many fonts that char doesn't exist
 %    and the slot is reused for random ligatures. So better not use it
@@ -679,7 +750,8 @@
 %    Alternatively we could just state that the symbol is unavailable in
 %    those fonts. For now I substitute.
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textpertenthousand} {\tc@check@symbol2\textpertenthousand}
+\DeclareTextCommandDefault{\textpertenthousand}
+                          {\tc@check@symbol2\textpertenthousand}
 \UndeclareTextCommand{\textpertenthousand}{T1}
 %    \end{macrocode}
 %
@@ -691,8 +763,10 @@
 %    symbols. In the higher-numbered sub-encodings we see only a few
 %    dropped additionally.
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textlangle}         {\tc@check@symbol3\textlangle}
-\DeclareTextCommandDefault{\textrangle}         {\tc@check@symbol3\textrangle}
+\DeclareTextCommandDefault{\textlangle}
+                          {\tc@check@symbol3\textlangle}
+\DeclareTextCommandDefault{\textrangle}
+                          {\tc@check@symbol3\textrangle}
 %    \end{macrocode}
 %
 %
@@ -702,14 +776,22 @@
 % \subsection{Sub-encoding \texttt{4}}
 %
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textcolonmonetary}  {\tc@check@symbol4\textcolonmonetary}
-\DeclareTextCommandDefault{\textdong}           {\tc@check@symbol4\textdong}
-\DeclareTextCommandDefault{\textdownarrow}      {\tc@check@symbol4\textdownarrow}
-\DeclareTextCommandDefault{\textleftarrow}      {\tc@check@symbol4\textleftarrow}
-\DeclareTextCommandDefault{\textlira}           {\tc@check@symbol4\textlira}
-\DeclareTextCommandDefault{\textrightarrow}     {\tc@check@symbol4\textrightarrow}
-\DeclareTextCommandDefault{\textuparrow}        {\tc@check@symbol4\textuparrow}
-\DeclareTextCommandDefault{\textwon}            {\tc@check@symbol4\textwon}
+\DeclareTextCommandDefault{\textcolonmonetary}
+                          {\tc@check@symbol4\textcolonmonetary}
+\DeclareTextCommandDefault{\textdong}
+                          {\tc@check@symbol4\textdong}
+\DeclareTextCommandDefault{\textdownarrow}
+                          {\tc@check@symbol4\textdownarrow}
+\DeclareTextCommandDefault{\textleftarrow}
+                          {\tc@check@symbol4\textleftarrow}
+\DeclareTextCommandDefault{\textlira}
+                          {\tc@check@symbol4\textlira}
+\DeclareTextCommandDefault{\textrightarrow}
+                          {\tc@check@symbol4\textrightarrow}
+\DeclareTextCommandDefault{\textuparrow}
+                          {\tc@check@symbol4\textuparrow}
+\DeclareTextCommandDefault{\textwon}
+                          {\tc@check@symbol4\textwon}
 %    \end{macrocode}
 %
 %
@@ -727,15 +809,17 @@
 %
 %    But the coverage is so random that it is impossible to sort them
 %    properly and if we tried to ensure that they only typeset those
-%    glyphs that are really  always available would put them all into
-%    sub-encoding \texttt{9} so that's a compromise really.
+%    glyphs that are really  always available, we would have to put them all into
+%    sub-encoding \texttt{9}; so putting them into 5 is really a compromise.
 %
-%    Modern fonts that don't typeset a tofu character if a glyph is
-%    missing are only cataloged as sub-encoding \texttt{5} if they
-%    really support of its glyph set.
+%    Modern fonts usually don't typeset a tofu character if a glyph is
+%    missing. They are therefore only classified as sub-encoding \texttt{5} if they
+%    really support its glyph set completely.
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textestimated}      {\tc@check@symbol5\textestimated}
-\DeclareTextCommandDefault{\textnumero}         {\tc@check@symbol5\textnumero}
+\DeclareTextCommandDefault{\textestimated}
+                          {\tc@check@symbol5\textestimated}
+\DeclareTextCommandDefault{\textnumero}
+                          {\tc@check@symbol5\textnumero}
 %    \end{macrocode}
 %
 %
@@ -744,8 +828,10 @@
 % \subsection{Sub-encoding \texttt{6}}
 %
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textflorin}         {\tc@check@symbol6\textflorin}
-\DeclareTextCommandDefault{\textcurrency}       {\tc@check@symbol6\textcurrency}
+\DeclareTextCommandDefault{\textflorin}
+                          {\tc@check@symbol6\textflorin}
+\DeclareTextCommandDefault{\textcurrency}
+                          {\tc@check@symbol6\textcurrency}
 %    \end{macrocode}
 %
 %
@@ -753,10 +839,14 @@
 % \subsection{Sub-encoding \texttt{7}}
 %
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textfractionsolidus}{\tc@check@symbol7\textfractionsolidus}
-\DeclareTextCommandDefault{\textohm}            {\tc@check@symbol7\textohm}
-\DeclareTextCommandDefault{\textmu}             {\tc@check@symbol7\textmu}
-\DeclareTextCommandDefault{\textminus}          {\tc@check@symbol7\textminus}
+\DeclareTextCommandDefault{\textfractionsolidus}
+                          {\tc@check@symbol7\textfractionsolidus}
+\DeclareTextCommandDefault{\textohm}
+                          {\tc@check@symbol7\textohm}
+\DeclareTextCommandDefault{\textmu}
+                          {\tc@check@symbol7\textmu}
+\DeclareTextCommandDefault{\textminus}
+                          {\tc@check@symbol7\textminus}
 %    \end{macrocode}
 %
 %
@@ -764,16 +854,19 @@
 % \subsection{Sub-encoding \texttt{8}}
 %
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textblank}          {\tc@check@symbol{8}\textblank}
-\DeclareTextCommandDefault{\textinterrobangdown}{\tc@check@symbol{8}\textinterrobangdown}
-\DeclareTextCommandDefault{\textinterrobang}    {\tc@check@symbol{8}\textinterrobang}
+\DeclareTextCommandDefault{\textblank}
+                          {\tc@check@symbol{8}\textblank}
+\DeclareTextCommandDefault{\textinterrobangdown}
+                          {\tc@check@symbol{8}\textinterrobangdown}
+\DeclareTextCommandDefault{\textinterrobang}
+                          {\tc@check@symbol{8}\textinterrobang}
 %    \end{macrocode}
 %
 %    Fonts with this sub-encoding don't have a Euro symbol, but
 %    instead of substituting we fake it.
 %    \begin{macrocode}
 \DeclareTextCommandDefault{\texteuro}
-            {\CheckEncodingSubset\UseTextSymbol{TS1}\tc@fake@euro{8}\texteuro}
+  {\CheckEncodingSubset\UseTextSymbol{TS1}\tc@fake@euro{8}\texteuro}
 %    \end{macrocode}
 %
 %
@@ -782,13 +875,20 @@
 % \subsection{Sub-encoding \texttt{9} (most missing)}
 %
 %    \begin{macrocode}
-\DeclareTextCommandDefault{\textcelsius}{\tc@check@symbol{9}\textcelsius}
-\DeclareTextCommandDefault{\textonesuperior}{\tc@check@symbol{9}\textonesuperior}
-\DeclareTextCommandDefault{\textthreequartersemdash}{\tc@check@symbol{9}\textthreequartersemdash}
-\DeclareTextCommandDefault{\textthreesuperior}{\tc@check@symbol{9}\textthreesuperior}
-\DeclareTextCommandDefault{\texttwelveudash}{\tc@check@symbol{9}\texttwelveudash}
-\DeclareTextCommandDefault{\texttwosuperior}{\tc@check@symbol{9}\texttwosuperior}
-\DeclareTextCommandDefault{\textbardbl}{\tc@check@symbol{9}\textbardbl}
+\DeclareTextCommandDefault{\textcelsius}
+                          {\tc@check@symbol{9}\textcelsius}
+\DeclareTextCommandDefault{\textonesuperior}
+                          {\tc@check@symbol{9}\textonesuperior}
+\DeclareTextCommandDefault{\textthreequartersemdash}
+                          {\tc@check@symbol{9}\textthreequartersemdash}
+\DeclareTextCommandDefault{\textthreesuperior}
+                          {\tc@check@symbol{9}\textthreesuperior}
+\DeclareTextCommandDefault{\texttwelveudash}
+                          {\tc@check@symbol{9}\texttwelveudash}
+\DeclareTextCommandDefault{\texttwosuperior}
+                          {\tc@check@symbol{9}\texttwosuperior}
+\DeclareTextCommandDefault{\textbardbl}
+                          {\tc@check@symbol{9}\textbardbl}
 %    \end{macrocode}
 %
 %
@@ -832,18 +932,18 @@
 %    \end{macrocode}
 %    These have Unicode slots so this should be integrated into TU explicitly
 %    \begin{macrocode}
-\DeclareTextSymbol{\textpilcrow}       \UnicodeEncodingName{"00B6}
-\DeclareTextSymbol{\textborn}          \UnicodeEncodingName{"002A}
-\DeclareTextSymbol{\textdied}          \UnicodeEncodingName{"2020}
-\DeclareTextSymbol{\textlbrackdbl}     \UnicodeEncodingName{"27E6}
-\DeclareTextSymbol{\textrbrackdbl}     \UnicodeEncodingName{"27E7}
-\DeclareTextSymbol{\textguarani}       \UnicodeEncodingName{"20B2}
+\DeclareTextSymbol{\textpilcrow}        \UnicodeEncodingName{"00B6}
+\DeclareTextSymbol{\textborn}           \UnicodeEncodingName{"002A}
+\DeclareTextSymbol{\textdied}           \UnicodeEncodingName{"2020}
+\DeclareTextSymbol{\textlbrackdbl}      \UnicodeEncodingName{"27E6}
+\DeclareTextSymbol{\textrbrackdbl}      \UnicodeEncodingName{"27E7}
+\DeclareTextSymbol{\textguarani}        \UnicodeEncodingName{"20B2}
 %    \end{macrocode}
 %    We could make \cs{textcentoldstyle} and \cs{textdollaroldstyle}
 %    point to dollar and cent in the Unicode encoding
 %    \begin{macrocode}
-%\DeclareTextSymbol{\textcentoldstyle}            \UnicodeEncodingName{"00A2}
-%\DeclareTextSymbol{\textdollaroldstyle}          \UnicodeEncodingName{"0024}
+%\DeclareTextSymbol{\textcentoldstyle}  \UnicodeEncodingName{"00A2}
+%\DeclareTextSymbol{\textdollaroldstyle}\UnicodeEncodingName{"0024}
 %    \end{macrocode}
 %    but I think it is better to pick them up from TS1 even if that
 %    usually means LMR fonts
@@ -908,7 +1008,8 @@
 \DeclareEncodingSubset{TS1}{lmss}    {1}
 \DeclareEncodingSubset{TS1}{lmssq}   {1}
 \DeclareEncodingSubset{TS1}{lmvtt}   {1}
-\DeclareEncodingSubset{TS1}{lmtt}    {1} % missing TM, SM, pertenthousand for some reason
+\DeclareEncodingSubset{TS1}{lmtt}    {1} % missing TM, SM and
+                                         % pertenthousand for some reason
 %    \end{macrocode}
 %
 %    \begin{macrocode}
@@ -918,33 +1019,33 @@
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\DeclareEncodingSubset{TS1}{bch}     {5}  % tofu for blank, ohm
-\DeclareEncodingSubset{TS1}{futj}    {5}  % tofu for blank, interrobang/down, ohm
-\DeclareEncodingSubset{TS1}{futs}    {5}  % tofu for blank, ohm
-\DeclareEncodingSubset{TS1}{futx}    {5}  % probably (currently broken distrib)
-\DeclareEncodingSubset{TS1}{pag}     {5}  % tofu for blank, interrobang/down, ohm
-\DeclareEncodingSubset{TS1}{pbk}     {5}  % tofu for blank, interrobang/down, ohm
-\DeclareEncodingSubset{TS1}{pcr}     {5}  % tofu for blank, interrobang/down, ohm
-\DeclareEncodingSubset{TS1}{phv}     {5}  % tofu for blank, interrobang/down, ohm
-\DeclareEncodingSubset{TS1}{pnc}     {5}  % tofu for blank, interrobang/down, ohm
-\DeclareEncodingSubset{TS1}{pplj}    {5}  % tofu for blank
-\DeclareEncodingSubset{TS1}{pplx}    {5}  % tofu for blank
-\DeclareEncodingSubset{TS1}{ppl}     {5}  % tofu for blank interrobang/down
-\DeclareEncodingSubset{TS1}{ptm}     {5}  % tofu for blank, interrobang/down, ohm
-\DeclareEncodingSubset{TS1}{pzc}     {5}  % tofu for blank, interrobang/down, ohm
-\DeclareEncodingSubset{TS1}{ul9}     {5}  % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{bch} {5} % tofu for blank, ohm
+\DeclareEncodingSubset{TS1}{futj}{5} % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{futs}{5} % tofu for blank, ohm
+\DeclareEncodingSubset{TS1}{futx}{5} % probably (currently broken distrib)
+\DeclareEncodingSubset{TS1}{pag} {5} % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{pbk} {5} % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{pcr} {5} % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{phv} {5} % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{pnc} {5} % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{pplj}{5} % tofu for blank
+\DeclareEncodingSubset{TS1}{pplx}{5} % tofu for blank
+\DeclareEncodingSubset{TS1}{ppl} {5} % tofu for blank interrobang/down
+\DeclareEncodingSubset{TS1}{ptm} {5} % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{pzc} {5} % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{ul9} {5} % tofu for blank, interrobang/down, ohm
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\DeclareEncodingSubset{TS1}{dayroms} {6}  % tofu for blank, interrobang/down, ohm
-\DeclareEncodingSubset{TS1}{dayrom}  {6}  % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{dayroms}{6} % tofu for blank, interrobang/down, ohm
+\DeclareEncodingSubset{TS1}{dayrom} {6} % tofu for blank, interrobang/down, ohm
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\DeclareEncodingSubset{TS1}{augie}   {8}  % really only missing euro
-\DeclareEncodingSubset{TS1}{put}     {8}
-\DeclareEncodingSubset{TS1}{uag}     {8}  % probably (currently broken distrib)
-\DeclareEncodingSubset{TS1}{ugq}     {8}
+\DeclareEncodingSubset{TS1}{augie}{8} % really only missing euro
+\DeclareEncodingSubset{TS1}{put}  {8}
+\DeclareEncodingSubset{TS1}{uag}  {8} % probably (currently broken distrib)
+\DeclareEncodingSubset{TS1}{ugq}  {8}
 %    \end{macrocode}
 %
 %    \begin{macrocode}
@@ -976,14 +1077,14 @@
 %    substituted.
 %
 %    \begin{macrocode}
-\DeclareEncodingSubset{TS1}{lato-*}                   {0}  % with a bunch of tofu inside
-\DeclareEncodingSubset{TS1}{opensans-*}               {0}  % with a bunch of tofu inside
-\DeclareEncodingSubset{TS1}{cantarell-*}              {0}  % with a bunch of tofu inside
-\DeclareEncodingSubset{TS1}{fbb-*}                    {0}  % missing centoldstyle
+\DeclareEncodingSubset{TS1}{lato-*}       {0}  % with a bunch of tofu inside
+\DeclareEncodingSubset{TS1}{opensans-*}   {0}  % with a bunch of tofu inside
+\DeclareEncodingSubset{TS1}{cantarell-*}  {0}  % with a bunch of tofu inside
+\DeclareEncodingSubset{TS1}{fbb-*}        {0}  % missing centoldstyle
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\DeclareEncodingSubset{TS1}{tli}                      {1}  % with lots of tofu inside
+\DeclareEncodingSubset{TS1}{tli}          {1}  % with lots of tofu inside
 %    \end{macrocode}
 %
 %    \begin{macrocode}
@@ -1109,7 +1210,7 @@
 \DeclareEncodingSubset{TS1}{erewhon-*}                {7}
 \DeclareEncodingSubset{TS1}{ComicNeue-TLF}            {7}
 \DeclareEncodingSubset{TS1}{ComicNeueAngular-TLF}     {7}
-\DeclareEncodingSubset{TS1}{Forum-LF}                 {7}  % the superiors are missing
+\DeclareEncodingSubset{TS1}{Forum-LF}      {7}  % the superiors are missing
 %    \end{macrocode}
 %
 %    \begin{macrocode}
@@ -1237,26 +1338,32 @@
 %<latexrelease>\let\textbrokenbar\@undefined
 %<latexrelease>\let\textcelsius\@undefined
 %<latexrelease>\let\textcent\@undefined
-%<latexrelease>\DeclareTextCommandDefault{\textcopyright}{\textcircled{c}}
+%<latexrelease>\DeclareTextCommandDefault{\textcopyright}
+%<latexrelease>                          {\textcircled{c}}
 %<latexrelease>\let\textdegree\@undefined
 %<latexrelease>\let\textdiv\@undefined
 %<latexrelease>\let\textlnot\@undefined
 %<latexrelease>\let\textonehalf\@undefined
 %<latexrelease>\let\textonequarter\@undefined
 %<latexrelease>\let\textonesuperior\@undefined
-%<latexrelease>\DeclareTextCommandDefault{\textordfeminine}{\textsuperscript{a}}
-%<latexrelease>\DeclareTextCommandDefault{\textordmasculine}{\textsuperscript{o}}
+%<latexrelease>\DeclareTextCommandDefault{\textordfeminine}
+%<latexrelease>                          {\textsuperscript{a}}
+%<latexrelease>\DeclareTextCommandDefault{\textordmasculine}
+%<latexrelease>                          {\textsuperscript{o}}
 %<latexrelease>\let\textpm\@undefined
 %<latexrelease>\let\textquotesingle\@undefined
 %<latexrelease>\let\textquotestraightbase\@undefined
 %<latexrelease>\let\textquotestraightdblbase\@undefined
-%<latexrelease>\DeclareTextCommandDefault{\textregistered}{\textcircled{%
-%<latexrelease>     \check@mathfonts\fontsize\sf@size\z@\math@fontsfalse\selectfont R}}
+%<latexrelease>\DeclareTextCommandDefault{\textregistered}
+%<latexrelease>    {\textcircled{%
+%<latexrelease>        \check@mathfonts\fontsize\sf@size\z@
+%<latexrelease>        \math@fontsfalse\selectfont R}}
 %<latexrelease>\let\textthreequartersemdash\@undefined
 %<latexrelease>\let\textthreequarters\@undefined
 %<latexrelease>\let\textthreesuperior\@undefined
 %<latexrelease>\let\texttimes\@undefined
-%<latexrelease>\DeclareTextCommandDefault{\texttrademark}{\textsuperscript{TM}}
+%<latexrelease>\DeclareTextCommandDefault{\texttrademark}
+%<latexrelease>                          {\textsuperscript{TM}}
 %<latexrelease>\let\texttwelveudash\@undefined
 %<latexrelease>\let\texttwosuperior\@undefined
 %<latexrelease>\let\textyen\@undefined
@@ -1433,9 +1540,12 @@
 %    kernel is info only). Using the package options you can change this behavior.
 % \changes{v2.0n}{2020/02/05}{Changed the package default to info (gh/262)}
 %    \begin{macrocode}
-\DeclareOption{error}{\gdef\tc@errorwarn{\PackageError{textcomp}}}
-\DeclareOption{warn}{\gdef\tc@errorwarn#1#2{\PackageWarning{textcomp}{#1}}}
-\DeclareOption{info}{\gdef\tc@errorwarn#1#2{\PackageInfo{textcomp}{#1}}}
+\DeclareOption{error}
+              {\gdef\tc@errorwarn{\PackageError{textcomp}}}
+\DeclareOption{warn}
+              {\gdef\tc@errorwarn#1#2{\PackageWarning{textcomp}{#1}}}
+\DeclareOption{info}
+              {\gdef\tc@errorwarn#1#2{\PackageInfo{textcomp}{#1}}}
 \DeclareOption{quiet}{\gdef\tc@errorwarn#1#2{}}
 %    \end{macrocode}
 %
@@ -1773,7 +1883,7 @@
 %    to ensure that |\textcurrency| is only typeset if the current
 %    font has a \texttt{TS1} subset id of less than 3. Otherwise
 %    |\tc@error| is called telling the user that for this font family
-%    |\textcurreny| is not available.
+%    |\textcurrency| is not available.
 %    \begin{macrocode}
 \def\tc@check@symbol{\CheckEncodingSubset\UseTextSymbol{TS1}\tc@subst}
 \def\tc@check@accent{\CheckEncodingSubset\UseTextAccent{TS1}\tc@error}
@@ -2008,7 +2118,7 @@
 %
 %    Finally input the encoding-specific definitions for
 %    \texttt{TS1} thus making the top-level definitions
-%    optimised for this encoding (and not for the default
+%    optimized for this encoding (and not for the default
 %    encoding).
 % \changes{v1.9o}{1998/03/20}{Load decls after defaults for speed.}
 %    \begin{macrocode}
diff --git a/Master/texmf-dist/source/latex-dev/base/ltthm.dtx b/Master/texmf-dist/source/latex-dev/base/ltthm.dtx
index c33ea4202fd..00fe97c77af 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltthm.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltthm.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltvers.dtx b/Master/texmf-dist/source/latex-dev/base/ltvers.dtx
index df57faf23b4..26eaee98901 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltvers.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltvers.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -33,7 +33,7 @@
 %<*driver>
 % \fi
 \ProvidesFile{ltvers.dtx}
-             [2020/12/05 v1.1e LaTeX Kernel (Version Info)]
+             [2021/01/15 v1.1e LaTeX Kernel (Version Info)]
 % \iffalse
 \documentclass{ltxdoc}
 \GetFileInfo{ltvers.dtx}
@@ -115,7 +115,7 @@
    {2021-05-01}
 %</2ekernel|latexrelease>
 %<*2ekernel>
-\def\patch@level{-1}
+\def\patch@level{-2}
 %    \end{macrocode}
 %
 % \begin{macro}{\development@branch@name}
@@ -181,28 +181,30 @@
 %    \begin{macrocode}
   \ifnum0\ifnum\patch@level=0 \ifx\development@branch@name\@empty 1\fi\fi>0 %
     \everyjob\expandafter{\the\everyjob
-      \typeout{\fmtname \space<\fmtversion>}}
+      \typeout{\fmtname\space <\fmtversion>}}
     \immediate
     \write16{\fmtname \space<\fmtversion>}
   \else\ifnum\patch@level>0
     \everyjob\expandafter{\the\everyjob
-      \typeout{\fmtname \space<\fmtversion> patch level \patch@level}}
+      \typeout{\fmtname\space <\fmtversion> patch level \patch@level}}
     \immediate
-    \write16{\fmtname \space<\fmtversion> patch level \patch@level}
+    \write16{\fmtname\space <\fmtversion> patch level \patch@level}
   \else
     \everyjob\expandafter{\the\everyjob
-      \typeout{\fmtname \space<\fmtversion> pre-release-\number-\patch@level\space
-        \ifx\development@branch@name\@undefined  \else
-          \ifx\development@branch@name\@empty  \else
-            \space (\development@branch@name\space branch)%
+      \typeout{\fmtname\space <\fmtversion>
+               pre-release-\number-\patch@level\space
+               \ifx\development@branch@name\@undefined  \else
+                 \ifx\development@branch@name\@empty  \else
+                  \space (\development@branch@name\space branch)%
           \fi
         \fi
     }}
     \immediate
-    \write16{\fmtname \space<\fmtversion> pre-release-\number-\patch@level\space
-        \ifx\development@branch@name\@undefined  \else
-          \ifx\development@branch@name\@empty  \else
-            \space (\development@branch@name\space branch)%
+    \write16{\fmtname\space <\fmtversion>
+             pre-release-\number-\patch@level\space
+            \ifx\development@branch@name\@undefined  \else
+             \ifx\development@branch@name\@empty  \else
+               \space (\development@branch@name\space branch)%
           \fi
         \fi
     }
diff --git a/Master/texmf-dist/source/latex-dev/base/ltxdoc.dtx b/Master/texmf-dist/source/latex-dev/base/ltxdoc.dtx
index e00f9bcb9f9..7a21f7d871f 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltxdoc.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltxdoc.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/ltxref.dtx b/Master/texmf-dist/source/latex-dev/base/ltxref.dtx
index 4e78deec4ad..dd482299b28 100644
--- a/Master/texmf-dist/source/latex-dev/base/ltxref.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/ltxref.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/makeindx.dtx b/Master/texmf-dist/source/latex-dev/base/makeindx.dtx
index c4a76ffabef..e8e48e60b06 100644
--- a/Master/texmf-dist/source/latex-dev/base/makeindx.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/makeindx.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -28,7 +28,7 @@
 % \fi
 %\iffalse
 % Copyright (C) 1985 by Leslie Lamport
-% Copyright (C) 1994-98 by \LaTeX3 Project and Johannes Braams
+% Copyright (C) 1994-98 by LaTeX Project and Johannes Braams
 %\fi
 %
 % \changes{1.0b}{1994/01/21}{added a missing \cs{end\{macro\}}, a
diff --git a/Master/texmf-dist/source/latex-dev/base/makeindx.ins b/Master/texmf-dist/source/latex-dev/base/makeindx.ins
index 771e3b12c6e..427d4c79674 100644
--- a/Master/texmf-dist/source/latex-dev/base/makeindx.ins
+++ b/Master/texmf-dist/source/latex-dev/base/makeindx.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/newdc.ins b/Master/texmf-dist/source/latex-dev/base/newdc.ins
index 0ea49996610..e2ce183f05e 100644
--- a/Master/texmf-dist/source/latex-dev/base/newdc.ins
+++ b/Master/texmf-dist/source/latex-dev/base/newdc.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/newlfont.dtx b/Master/texmf-dist/source/latex-dev/base/newlfont.dtx
index 085d2348ba8..3b6e001075b 100644
--- a/Master/texmf-dist/source/latex-dev/base/newlfont.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/newlfont.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/nfssfont.dtx b/Master/texmf-dist/source/latex-dev/base/nfssfont.dtx
index 09d91dc51d5..554c7ae8f07 100644
--- a/Master/texmf-dist/source/latex-dev/base/nfssfont.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/nfssfont.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/nfssfont.ins b/Master/texmf-dist/source/latex-dev/base/nfssfont.ins
index 24a2e115e07..7d1b9cc41ae 100644
--- a/Master/texmf-dist/source/latex-dev/base/nfssfont.ins
+++ b/Master/texmf-dist/source/latex-dev/base/nfssfont.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/olddc.ins b/Master/texmf-dist/source/latex-dev/base/olddc.ins
index 7401e29f6d6..d878507d8e3 100644
--- a/Master/texmf-dist/source/latex-dev/base/olddc.ins
+++ b/Master/texmf-dist/source/latex-dev/base/olddc.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/oldlfont.dtx b/Master/texmf-dist/source/latex-dev/base/oldlfont.dtx
index 56204af7ae4..d04ddb6323b 100644
--- a/Master/texmf-dist/source/latex-dev/base/oldlfont.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/oldlfont.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/preload.dtx b/Master/texmf-dist/source/latex-dev/base/preload.dtx
index 22554b429fd..b2ca24bce5b 100644
--- a/Master/texmf-dist/source/latex-dev/base/preload.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/preload.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/proc.dtx b/Master/texmf-dist/source/latex-dev/base/proc.dtx
index 814006e411b..7a1329fb82c 100644
--- a/Master/texmf-dist/source/latex-dev/base/proc.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/proc.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -28,8 +28,8 @@
 % \fi
 %
 % \iffalse
-% Copyright (C) 1991,1992 by Leslie Lamport \and
-% Copyright (C) 1994-2020 by the \LaTeX3 project \and Johannes Braams
+% Copyright (C) 1991,1992 by Leslie Lamport and
+% Copyright (C) 1994-2020 by the LaTeX Project and Johannes Braams
 %
 % \changes{v1.1}{1994/01/25}{Made `proc' a document class and provide
 %    a .sty file for compatibility mode}
diff --git a/Master/texmf-dist/source/latex-dev/base/proc.ins b/Master/texmf-dist/source/latex-dev/base/proc.ins
index b9c3cbe0645..cfed5bd6a39 100644
--- a/Master/texmf-dist/source/latex-dev/base/proc.ins
+++ b/Master/texmf-dist/source/latex-dev/base/proc.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/slides.dtx b/Master/texmf-dist/source/latex-dev/base/slides.dtx
index 9c83a3d851a..883e7d34f04 100644
--- a/Master/texmf-dist/source/latex-dev/base/slides.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/slides.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -28,7 +28,7 @@
 % \fi
 %
 % \iffalse
-% Copyright (C) 1994-97 LaTeX3 project, Frank Mittelbach
+% Copyright (C) 1994-97 LaTeX Project, Frank Mittelbach
 % and Rainer Sch\"opf, all rights reserved.
 %
 %    \begin{macrocode}
diff --git a/Master/texmf-dist/source/latex-dev/base/slides.ins b/Master/texmf-dist/source/latex-dev/base/slides.ins
index 1213d4f4d90..43ec2bebdf8 100644
--- a/Master/texmf-dist/source/latex-dev/base/slides.ins
+++ b/Master/texmf-dist/source/latex-dev/base/slides.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
@@ -97,7 +97,7 @@ extension .ins) which are part of the distribution.
 This is a generated file.
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
@@ -139,7 +139,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/slifonts.fdd b/Master/texmf-dist/source/latex-dev/base/slifonts.fdd
index d3951cfa574..ec8b802596f 100644
--- a/Master/texmf-dist/source/latex-dev/base/slifonts.fdd
+++ b/Master/texmf-dist/source/latex-dev/base/slifonts.fdd
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright 1993-2019
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -30,7 +30,7 @@
 %\iffalse        This is a META comment
 %
 % File `slifonts.fdd'.
-% Copyright (C) 1989-1998 LaTeX3 project, Frank Mittelbach and
+% Copyright (C) 1989-1998 LaTeX Project, Frank Mittelbach and
 % Rainer Sch\"opf, all rights reserved.
 %
 %<lcmss&!ec>\ProvidesFile{ot1lcmss.fd}
diff --git a/Master/texmf-dist/source/latex-dev/base/syntonly.dtx b/Master/texmf-dist/source/latex-dev/base/syntonly.dtx
index 55b2ad3cec6..b214c49ae4a 100644
--- a/Master/texmf-dist/source/latex-dev/base/syntonly.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/syntonly.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/syntonly.ins b/Master/texmf-dist/source/latex-dev/base/syntonly.ins
index 3717d1e6fe8..6b4113ed115 100644
--- a/Master/texmf-dist/source/latex-dev/base/syntonly.ins
+++ b/Master/texmf-dist/source/latex-dev/base/syntonly.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 1993-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/tulm.fdd b/Master/texmf-dist/source/latex-dev/base/tulm.fdd
index 9308d801ff2..5c1566a5bad 100644
--- a/Master/texmf-dist/source/latex-dev/base/tulm.fdd
+++ b/Master/texmf-dist/source/latex-dev/base/tulm.fdd
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright 2016-2019
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -30,7 +30,7 @@
 %\iffalse        This is a META comment
 %
 % File `cmfonts.fdd'.
-% Copyright (C) 2016-2019 LaTeX3 Project
+% Copyright (C) 2016-2019 LaTeX Project
 %
 %
 %<TUlmr>\ProvidesFile{tulmr.fd}
@@ -51,7 +51,7 @@
 \title{The file \texttt{tulm.fdd} for use with
       \LaTeXe.\thanks{This file has version
            number \fileversion, dated \filedate.}}
-\date{\filedate}\author{LaTeX3 Project}
+\date{\filedate}\author{\LaTeX\ Project}
 \addtolength\textwidth{30pt}
 \begin{document}
 \MaintainedByLaTeXTeam{latex}
diff --git a/Master/texmf-dist/source/latex-dev/base/tulm.ins b/Master/texmf-dist/source/latex-dev/base/tulm.ins
index 1c4e45e8c42..98962f2b207 100644
--- a/Master/texmf-dist/source/latex-dev/base/tulm.ins
+++ b/Master/texmf-dist/source/latex-dev/base/tulm.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 2016-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
@@ -49,7 +49,7 @@ reports for it can be opened at https://latex-project.org/bugs.html
 
 
 Copyright (C) 2016-2021
-The LaTeX3 Project and any individual authors listed elsewhere
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/unpack.ins b/Master/texmf-dist/source/latex-dev/base/unpack.ins
index 9df3403f5b3..6332fcb5c00 100644
--- a/Master/texmf-dist/source/latex-dev/base/unpack.ins
+++ b/Master/texmf-dist/source/latex-dev/base/unpack.ins
@@ -4,7 +4,7 @@
 %% LaTeX or TeX.
 %%
 %% Copyright (C) 1993-2021
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the LaTeX base system.
diff --git a/Master/texmf-dist/source/latex-dev/base/utf8ienc.dtx b/Master/texmf-dist/source/latex-dev/base/utf8ienc.dtx
index cd11cb0f2ae..79c725915c7 100644
--- a/Master/texmf-dist/source/latex-dev/base/utf8ienc.dtx
+++ b/Master/texmf-dist/source/latex-dev/base/utf8ienc.dtx
@@ -1,7 +1,7 @@
 % \iffalse meta-comment
 %
 % Copyright (C) 1993-2021
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the LaTeX base system.
@@ -216,7 +216,7 @@
 %<+ts1> \ProvidesFile{ts1enc.dfu}
 %<+x2>  \ProvidesFile{x2enc.dfu}
 %<+all> \ProvidesFile{utf8enc.dfu}
-%<-utf8-2018>   [2020/11/26 v1.2k UTF-8 support for inputenc]
+%<-utf8-2018>   [2021/01/27 v1.2l UTF-8 support for inputenc]
 %    \end{macrocode}
 %
 %    \begin{macrocode}
@@ -1137,7 +1137,7 @@
 % \changes{v1.1q}{2015/12/02}{Add remaining latin uses of accents in T1}
 % \changes{v1.1r}{2015/12/03}{Add some more ogonek cases}
 % \changes{v1.1s}{2016/01/11}{Add some more caron and acute}
-% \changes{v1.1t}{2017/01/28}{Add caron cominations for GgYy}
+% \changes{v1.1t}{2017/01/28}{Add caron combinations for GgYy}
 %    \begin{macrocode}
 %<all,t1,ot1,ly1>\DeclareUnicodeCharacter{00A0}{\nobreakspace}
 %<all,t1,ot1,ly1>\DeclareUnicodeCharacter{00A1}{\textexclamdown}
@@ -1701,6 +1701,18 @@
 %<all,ts1>\DeclareUnicodeCharacter{0E3F}{\textbaht}
 %<all,t1>\DeclareUnicodeCharacter{1E02}{\.B}
 %<all,t1>\DeclareUnicodeCharacter{1E03}{\.b}
+%    \end{macrocode}
+% \changes{v1.2k}{2021/01/27}{Added various additional dot accents (gh/484)}
+%    \begin{macrocode}
+%<all,t1>\DeclareUnicodeCharacter{1E0D}{\d d}
+%<all,t1>\DeclareUnicodeCharacter{1E25}{\d h}
+%<all,t1>\DeclareUnicodeCharacter{1E37}{\d l}
+%<all,t1>\DeclareUnicodeCharacter{1E43}{\d m}
+%<all,t1>\DeclareUnicodeCharacter{1E45}{\.n}
+%<all,t1>\DeclareUnicodeCharacter{1E47}{\d n}
+%<all,t1>\DeclareUnicodeCharacter{1E5B}{\d r}
+%<all,t1>\DeclareUnicodeCharacter{1E63}{\d s}
+%<all,t1>\DeclareUnicodeCharacter{1E6D}{\d t}
 %<all,t1>\DeclareUnicodeCharacter{1E9E}{\SS}
 %<all,x2,t2c,t2b,t2a,t1,utf8>\DeclareUnicodeCharacter{200C}{\textcompwordmark}
 %    \end{macrocode}
diff --git a/Master/texmf-dist/source/latex-dev/tools/afterpage.dtx b/Master/texmf-dist/source/latex-dev/tools/afterpage.dtx
index 600d221cb63..e5fa69f5152 100644
--- a/Master/texmf-dist/source/latex-dev/tools/afterpage.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/afterpage.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/afterpage.ins b/Master/texmf-dist/source/latex-dev/tools/afterpage.ins
index 96cba1ed0ca..0cfc531f193 100644
--- a/Master/texmf-dist/source/latex-dev/tools/afterpage.ins
+++ b/Master/texmf-dist/source/latex-dev/tools/afterpage.ins
@@ -3,8 +3,8 @@
 %% driver files from the doc files in this package when run through
 %% LaTeX or TeX.
 %%
-%% Copyright (C) 1993-2020
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% Copyright (C) 1993-2021
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the Standard LaTeX `Tools Bundle'.
@@ -45,8 +45,8 @@ The source is maintained by the LaTeX Project team and bug
 reports for it can be opened at https://latex-project.org/bugs/
 (but please observe conditions on bug reports sent to that address!)
 
-Copyright (C) 1993-2020
-The LaTeX3 Project and any individual authors listed elsewhere
+Copyright (C) 1993-2021
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/array.dtx b/Master/texmf-dist/source/latex-dev/tools/array.dtx
index ff963d7f514..1ca08036d95 100644
--- a/Master/texmf-dist/source/latex-dev/tools/array.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/array.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
@@ -33,7 +33,7 @@
 %<+package>\DeclareCurrentRelease{}{2020-10-01}
 %<+package>
 %<+package>\ProvidesPackage{array}
-%<+package>         [2020/10/01 v2.5c Tabular extension package (FMi)]
+%<+package>         [2021/02/10 v2.5d Tabular extension package (FMi)]
 %
 % \fi
 %
@@ -188,7 +188,7 @@
 %         David Carlisle\thanks{David kindly agreed on the inclusion
 %         of the \texttt{\textbackslash{}newcolumntype} implementation,
 %         formerly in
-%         \texttt{newarray.sty} into this package }}
+%         \texttt{newarray.sty} into this package.}}
 %
 % \date{Printed \today}
 %
@@ -361,6 +361,56 @@
 %       columns have predefined widths.
 % \end{itemize}
 %
+%
+% \subsection{The behavior of the \texttt{\string\\} command}
+%
+% In the basic \texttt{tabular} implementation of \LaTeX{} the \cs{\bslash}
+% command ending the rows of the \texttt{tabular} or \texttt{array} has
+% a somewhat inconsistent behavior if its optional argument is used. The
+% result then depends on the type of rightmost column and as remarked in
+% Leslie Lamport's \LaTeX{} manual~\cite{bk:lamport} may not always produce the
+% expected extra space.
+%
+%
+% Without the \textsf{array} package the extra space requested by the
+% optional argument of \cs{\bslash} is measured from the last baseline of
+% the rightmost column (indicated by ``x'' in the following
+% example). As a result, swapping the column will give different
+% results:
+% \begin{verbatim}
+%   \begin{tabular}[t]{lp{1cm}}
+%       1 & 1\newline x   \\[20pt]     2 & 2    \end{tabular}
+%   \begin{tabular}[t]{p{1cm}l}
+%       1\newline 1 & x   \\[20pt]     2 & 2    \end{tabular}
+%   \end{verbatim}
+% \pagebreak
+% If you run this without the \textsf{array} package you will get the
+% following result:
+% \begin{center}
+% \begin{tabular}[t]{lp{1cm}}
+%   1 & 1\newline x \\[32pt]      2 & 2 \end{tabular}
+% \begin{tabular}[t]{p{1cm}l}
+%   1\newline 1 & x \\[20pt]      2 & 2 \end{tabular}
+% \end{center}
+% In contrast, when the \textsf{array} package is loaded, the requested
+% space in the optional argument is always measured from the baseline of
+% the whole row and not from the last baseline of the rightmost column, thus
+% swapping columns doesn't change the spacing and we same table height
+% with an effective 8pt of extra space (as the second line already takes
+% up 12pt of the requested 20pt):
+% \begin{center}
+% \begin{tabular}[t]{lp{1cm}}
+%   1 & 1\newline x \\[20pt]      2 & 2 \end{tabular}
+% \begin{tabular}[t]{p{1cm}l}
+%   1\newline 1 & x \\[20pt]      2 & 2 \end{tabular}
+% \end{center}
+%
+% This correction of behavior only makes a difference if the rightmost column
+% is a \texttt{p}-column. Thus if you add the \textsf{array}
+% package to an existing document, you should verify the spacing in all
+% tables that have this kind of structure.
+%
+%
 % \subsection{Defining new column specifiers}
 %
 % \DeleteShortVerb{\=}
@@ -1958,8 +2008,9 @@
 % \changes{v2.2d}{1994/05/16}{Use \LaTeXe \cs{@finalstrut}}
 % \changes{v2.3g}{1996/05/07}{Add \cs{hfil} for tools/2120}
 % \changes{v2.4i}{2018/09/13}{Add group to prevent color leak (gh/72)}
+% \changes{v2.5d}{2021/02/10}{Explicitly run \cs{par} at the end of pboxes}
 %    \begin{macrocode}
-\def\@endpbox{\@finalstrut\@arstrutbox \color@endgroup \egroup\hfil}
+\def\@endpbox{\@finalstrut\@arstrutbox \par \color@endgroup \egroup\hfil}
 %    \end{macrocode}
 % \end{macro}
 %
diff --git a/Master/texmf-dist/source/latex-dev/tools/bm.dtx b/Master/texmf-dist/source/latex-dev/tools/bm.dtx
index 096f6c4bc2a..80c73f57189 100644
--- a/Master/texmf-dist/source/latex-dev/tools/bm.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/bm.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/bm.ins b/Master/texmf-dist/source/latex-dev/tools/bm.ins
index e963d1d88e2..c00a3e5cca4 100644
--- a/Master/texmf-dist/source/latex-dev/tools/bm.ins
+++ b/Master/texmf-dist/source/latex-dev/tools/bm.ins
@@ -3,8 +3,8 @@
 %% driver files from the doc files in this package when run through
 %% LaTeX or TeX.
 %%
-%% Copyright (C) 1993-2020
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% Copyright (C) 1993-2021
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the Standard LaTeX `Tools Bundle'.
@@ -45,8 +45,8 @@ The source is maintained by the LaTeX Project team and bug
 reports for it can be opened at https://latex-project.org/bugs/
 (but please observe conditions on bug reports sent to that address!)
 
-Copyright (C) 1993-2020
-The LaTeX3 Project and any individual authors listed elsewhere
+Copyright (C) 1993-2021
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/calc.dtx b/Master/texmf-dist/source/latex-dev/tools/calc.dtx
index 62fe27489b2..78b6167fe6f 100644
--- a/Master/texmf-dist/source/latex-dev/tools/calc.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/calc.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
@@ -25,7 +25,7 @@
 %% Copyright (C) 1992--1995
 %%          Kresten Krab Thorup and Frank Jensen.
 %% Copyright (C) 1997--2007
-%%          Kresten Krab Thorup, Frank Jensen and the LaTeX3 Project.
+%%          Kresten Krab Thorup, Frank Jensen and the LaTeX Project.
 %%
 %% The original authors (fj@hugin.dk and  krab@daimi.aau.dk) have
 %% contributed this package to the LaTeX distribution.
diff --git a/Master/texmf-dist/source/latex-dev/tools/dcolumn.dtx b/Master/texmf-dist/source/latex-dev/tools/dcolumn.dtx
index 1899cce5560..069e633221d 100644
--- a/Master/texmf-dist/source/latex-dev/tools/dcolumn.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/dcolumn.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/delarray.dtx b/Master/texmf-dist/source/latex-dev/tools/delarray.dtx
index 17cac2052cb..cc503707b0d 100644
--- a/Master/texmf-dist/source/latex-dev/tools/delarray.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/delarray.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/enumerate.dtx b/Master/texmf-dist/source/latex-dev/tools/enumerate.dtx
index 3ce463e6015..150a7386b83 100644
--- a/Master/texmf-dist/source/latex-dev/tools/enumerate.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/enumerate.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/fileerr.dtx b/Master/texmf-dist/source/latex-dev/tools/fileerr.dtx
index 16a95e28203..d9163041161 100644
--- a/Master/texmf-dist/source/latex-dev/tools/fileerr.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/fileerr.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/fontsmpl.dtx b/Master/texmf-dist/source/latex-dev/tools/fontsmpl.dtx
index a5fb2964a98..b7208267736 100644
--- a/Master/texmf-dist/source/latex-dev/tools/fontsmpl.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/fontsmpl.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/ftnright.dtx b/Master/texmf-dist/source/latex-dev/tools/ftnright.dtx
index e5fffdfcd92..e8da56aa204 100644
--- a/Master/texmf-dist/source/latex-dev/tools/ftnright.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/ftnright.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
@@ -314,7 +314,7 @@
 % \newblock Addison-Wesley, Reading, Massachusetts, 1986.
 %
 % \bibitem{src:ltxiii94}
-% \LaTeX3 project.
+% \LaTeX\ Project.
 % \newblock \LaTeXe distribution, 1994.
 % \newblock Sources for {\LaTeXe} the successor to \LaTeX~2.09.
 %
diff --git a/Master/texmf-dist/source/latex-dev/tools/hhline.dtx b/Master/texmf-dist/source/latex-dev/tools/hhline.dtx
index b9234b5aa25..98d68024515 100644
--- a/Master/texmf-dist/source/latex-dev/tools/hhline.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/hhline.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/indentfirst.dtx b/Master/texmf-dist/source/latex-dev/tools/indentfirst.dtx
index 7123be04c54..e54df284ae1 100644
--- a/Master/texmf-dist/source/latex-dev/tools/indentfirst.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/indentfirst.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/layout.dtx b/Master/texmf-dist/source/latex-dev/tools/layout.dtx
index 8918ffdca48..6962674255b 100644
--- a/Master/texmf-dist/source/latex-dev/tools/layout.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/layout.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
@@ -30,7 +30,7 @@
 %<+package>\ProvidesPackage{layout}
 %<+driver>\ProvidesFile{layout.drv}
 %\ProvidesFile{layout.dtx}
-                [2014/10/28 v1.2c Show layout parameters]
+                [2020-07-25 v1.2d Show layout parameters]
 %
 %    A short driver is provided that can be extracted if necessary by
 %    the \textsf{DocStrip} program provided with \LaTeXe.
@@ -54,6 +54,17 @@
 % \changes{v1.1d}{1994/09/08}{Stored texts in control sequences to
 %    allow other languages}
 %
+% \makeatletter
+% \def\allowtofu{^^A
+%\def\UTFviii@undefined@err##1{^^A
+%  \PackageWarning{inputenc}{Unicode character \expandafter
+%                          \UTFviii@splitcsname\string##1\relax
+%                          \MessageBreak
+%                          not set up for use with LaTeX}^^A
+%  \raisebox{.8pt}{\fboxsep1pt\kern.1pt\fbox{$\cdot$}\kern.1pt}^^A
+%   }}
+% \makeatother
+%
 % \GetFileInfo{layout.dtx}
 % \title{Displaying page layout variables}
 % \author{Kent McPherson a.o.\thanks{Converted for \LaTeXe\ by
@@ -172,6 +183,20 @@
   \def\notshown{non mostrato}
   }
 %    \end{macrocode}
+%    
+%    \changes{v1.2d}{2020-07-25}{Added option for Japanese (gh353)}
+% \begin{allowtofu}
+%    \begin{macrocode}
+\DeclareOption{japanese}{%
+  \def\Headertext{天}
+  \def\Bodytext{基本版面}
+  \def\Footertext{地}
+  \def\MarginNotestext{傍\\注}
+  \def\oneinchtext{1インチ}
+  \def\notshown{非表示}
+  }
+%    \end{macrocode}
+% \end{allowtofu}
 %
 %    This package has an option \Lopt{verbose}. Using it will make the
 %    command |\layout| type some of the parameters on the terminal.
diff --git a/Master/texmf-dist/source/latex-dev/tools/longtable.dtx b/Master/texmf-dist/source/latex-dev/tools/longtable.dtx
index 004d630fcec..c236aabb205 100644
--- a/Master/texmf-dist/source/latex-dev/tools/longtable.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/longtable.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
@@ -27,11 +27,17 @@
           \ProvidesFile{longtable.dtx}
 %</dtx>
 %<package>\NeedsTeXFormat{LaTeX2e}[1995/06/01]
+%<package>\providecommand\DeclareRelease[3]{}
+%<package>\providecommand\DeclareCurrentRelease[2]{}
+%<package>
+%<package>\DeclareRelease{}{2020-01-02}{longtable-2020-01-07.sty}
+%<package>\DeclareCurrentRelease{}{2020-02-07}
+%<package>
 %<package>\ProvidesPackage{longtable}
 %<driver> \ProvidesFile{longtable.drv}
 % \fi
 %         \ProvidesFile{longtable.dtx}
-          [2020/01/07 v4.13 Multi-page Table package (DPC)]
+          [2020-02-07 v4.14 Multi-page Table package (DPC)]
 %
 % \iffalse
 %<*driver>
@@ -303,7 +309,7 @@
 % (see below), the "LTchunksize" must be at least  as large as the
 % number of rows in each of the head or foot sections.
 %
-% This document specifies "\setcounter{LTchunksize}{10}".  If you look
+% This document specifies "\setcounter{LTchunksize}{200}".  If you look
 % at the previous table, after the \emph{first} run of \LaTeX\  you will
 % see that various parts of the table do not line up.
 % \LaTeX\ will also have printed a warning that the column
@@ -877,9 +883,11 @@
 % \end{macro}
 %
 % \begin{macro}{\LTchunksize}
-% Chunk size (The number of rows taken per "\halign"). Default 20.
+% \changes{v4.14}{2020/02/07}
+%      {Increase default chunksize from 20 to 200}
+% Chunk size (The number of rows taken per "\halign"). Default 200.
 %    \begin{macrocode}
-\newcount\LTchunksize \LTchunksize=20
+\newcount\LTchunksize \LTchunksize=200
 %    \end{macrocode}
 % \end{macro}
 %
@@ -916,6 +924,14 @@
 % \end{macro}
 % \end{macro}
 %
+% \begin{macro}{\LT@gbox}
+% \changes{v4.14}{2020/02/07}
+%      {global box added (tools/2914)}
+%    \begin{macrocode}
+\newbox\LT@gbox
+%    \end{macrocode}
+% \end{macro}
+%
 % \begin{macro}{\LT@cols}
 % Counter for number of columns.
 %    \begin{macrocode}
@@ -1212,7 +1228,7 @@
 % \end{macro}
 %
 % \begin{macro}{\LT@start}
-% % \changes{v4.13}{2020/01/07}
+% \changes{v4.13}{2020/01/07}
 %      {fix issue https://github.com/davidcarlisle/dpctex/issues/8}
 % This macro starts the process of putting the table on the current
 % page. It is not called until either a "\\" or "\endlongtable" command
@@ -1228,6 +1244,34 @@
   \let\LT@start\endgraf
   \endgraf\penalty\z@\vskip\LTpre\endgraf
 %    \end{macrocode}
+% \changes{v4.14}{2020/02/07}
+%      {Guard against shrink glue on current page tools/3396 and github 183}
+% This next block was suggested by Lars Hellström in pr tools/3396
+% He documents it as:
+%
+% The original problem occurs because TeX has not yet found an awfully bad
+% "(b=*)" breakpoint and is therefore still collecting material to see if there
+% is a really good break somewhere just ahead. As we know there aren't, we
+% want to make it stop looking and break the page, so that "\pagetotal" will be
+% for the page  where the table will actually end up. To achieve this, we
+% need to give \TeX\ an awfully bad, but legal, breakpoint. The simplest way of
+% doing this seems to be to insert a "\kern" that counters the "\pageshrink" for
+% the page, followed by a "\penalty" and a "\par" (to exercise the page builder).
+% We also have to make sure that this breakpoint doesn't affect how the next
+% page is broken, so we make the penalty 9999 (10000 is infinite and thus not
+% a legal breakpoint) and cancel out the "\kern" with a new "\kern".
+% 
+% I don't think this is the \emph{right} solution to the problem (that would be
+% that the standard output routine has a feature for syncronizing with
+% typesetting, as part of the preparations for switching output routine), but
+% it's OK. Perhaps XOR will make it better.
+%    \begin{macrocode}
+   \ifdim \pagetotal<\pagegoal \else
+      \dimen@=\pageshrink
+      \advance \dimen@ 1sp %
+      \kern\dimen@\penalty 9999\endgraf \kern-\dimen@
+   \fi
+%    \end{macrocode}
 % Start a new page if there is not enough room for the table head, foot,
 % and one extra line.
 %    \begin{macrocode}
@@ -1259,7 +1303,18 @@
 %
 %    \begin{macrocode}
   \advance\dimen@ -\pagegoal
-  \ifdim \dimen@>\z@\vfil\break\fi
+  \ifdim \dimen@>\z@
+    \vfil\break
+  \else
+%    \end{macrocode}
+%
+% \changes{v4.14}{2020/02/07}
+%      {Guard against shrink glue on current page see github 183}
+% The LT output routine does not handle shrink on the page, which can cause
+% The first page to be over-long, so forget it is there.
+%    \begin{macrocode}
+    \ifdim\pageshrink>\z@\pageshrink\z@\fi
+  \fi
 %    \end{macrocode}
 % Store height of page minus table foot in  "\@colroom".
 % \changes{v3.14}{1995/05/02}
@@ -1269,9 +1324,12 @@
 %    \end{macrocode}
 % If the foot is non empty, reduce the "\vsize" and "\@colroom"
 % accordingly.
+% \changes{v4.14}{2020/02/07}
+%      {Rearrange vertical space tests for tools/3512 (floats on same page)}
 %    \begin{macrocode}
   \ifvoid\LT@foot\else
-    \advance\vsize-\ht\LT@foot
+%    \advance\vsize-\ht\LT@foot
+    \global\advance\vsize-\ht\LT@foot
     \global\advance\@colroom-\ht\LT@foot
     \dimen@\pagegoal\advance\dimen@-\ht\LT@foot\pagegoal\dimen@
     \maxdepth\z@
@@ -1350,8 +1408,15 @@
   \fi
 %    \end{macrocode}
 % Force one more go with the \env{longtable} output routine.
+% \changes{v4.14}{2020/02/07}
+%      {Rearrange vertical space tests for tools/3512 (floats on same page)}
 %    \begin{macrocode}
   \endgraf\penalty -\LT@end@pen
+  \ifvoid\LT@foot\else
+    \global\advance\vsize\ht\LT@foot
+    \global\advance\@colroom\ht\LT@foot
+    \dimen@\pagegoal\advance\dimen@\ht\LT@foot\pagegoal\dimen@
+  \fi
 %    \end{macrocode}
 % Now close the group to return to the standard routine.
 %    \begin{macrocode}
@@ -1361,9 +1426,11 @@
 % table.\footnote{This can not be the correct. However if it is omitted,
 % there is a problem with marginpars, for example on page~3 of this
 % document. Any Output Routine Gurus out there?}
+% \changes{v4.14}{2020/02/07}
+%      {Rearrange vertical space tests for tools/3512 (floats on same page)}
 %    \begin{macrocode}
   \global\@mparbottom\z@
-  \pagegoal\vsize
+%  \pagegoal\vsize
   \endgraf\penalty\z@\addvspace\LTpost
 %    \end{macrocode}
 % Footnotes. As done in  the \package{multicol} package.
@@ -1452,6 +1519,8 @@
 % \begin{macro}{\LT@setprevdepth}
 % \changes{v4.05}{1996/11/12}
 %      {Macro added}
+% \changes{v4.14}{2020/02/07}
+%      {spurious \cs{global} removed}
 % This will be redefined to set the "\prevdepth"
 %  at the start of a chunk.
 %    \begin{macrocode}
@@ -1471,7 +1540,7 @@
   \global\advance\LT@rows\@ne
   \ifnum\LT@rows=\LTchunksize
     \gdef\LT@setprevdepth{%
-      \prevdepth\z@\global
+      \prevdepth\z@
       \global\let\LT@setprevdepth\relax}%
     \expandafter\LT@xtabularcr
   \else
@@ -1528,11 +1597,13 @@
 % \begin{macro}{\LT@echunk}
 % \changes{v4.05}{1996/11/12}
 %      {\cs{unskip} added for pagebreak support}
+% \changes{v4.14}{2020/02/07}
+%      {allocated global box  (tools/2914)}
 % This ends the current chunk, and removes the dummy row.
 %    \begin{macrocode}
 \def\LT@echunk{%
   \crcr\LT@save@row\cr\egroup
-  \global\setbox\@ne\lastbox
+  \global\setbox\LT@gbox\lastbox
 %    \end{macrocode}
 % The following line was added in v4.05.
 % \package{longtable} relies on "\lineskip" glue (which is 0pt) to
@@ -1753,9 +1824,11 @@
 % Loop through the last row, discarding glue, and saving box widths. At
 % V3.04 changed the scratch box to 2, as the new "\kill" requires that
 % "\box0" be preserved.
+% \changes{v4.14}{2020/02/07}
+%      {allocated global box  (tools/2914)}
 %    \begin{macrocode}
   \setbox\tw@\hbox{%
-    \unhbox\@ne
+    \unhbox\LT@gbox
     \let\LT@old@row\LT@save@row
     \global\let\LT@save@row\@empty
     \count@\LT@cols
@@ -1973,13 +2046,17 @@
 % vsplit off a bit of the last chunk, so that the last page did not just
 % have head and foot sections, but it is hard to do this in a consistent
 % manner.}
+% \changes{v4.14}{2020/02/07}
+%      {Rearrange vertical space tests for tools/3512 (floats on same page)}
 %    \begin{macrocode}
         \dimen@\pagegoal
+        \advance\dimen@\ht\LT@foot
         \advance\dimen@-\ht\LT@lastfoot
         \ifdim\dimen@<\ht\z@
           \setbox\@cclv\vbox{\unvbox\z@\copy\LT@foot\vss}%
           \@makecol
           \@outputpage
+          \global\vsize\@colroom
           \setbox\z@\vbox{\box\LT@head}%
 %    \end{macrocode}
 % End of "\ifdim\dimen@<\ht\@cclc".
@@ -1993,14 +2070,17 @@
 % Reset "\@colroom".
 % \changes{v3.14}{1995/05/02}
 %      {Reset \cs{@colroom}, for tools/1584}
+% \changes{v4.14}{2020/02/07}
+%      {Rearrange vertical space tests for tools/3512 (floats on same page)}
 %    \begin{macrocode}
-      \global\@colroom\@colht
-      \global\vsize\@colht
+%      \global\@colroom\@colht
+%      \global\vsize\@colht
 %    \end{macrocode}
 % Put the last page of the table on to the main vertical list.
+% \changes{v4.14}{2020/02/07}
+%      {Remove box from final page tools/3512}
 %    \begin{macrocode}
-      \vbox
-        {\unvbox\z@\box\ifvoid\LT@lastfoot\LT@foot\else\LT@lastfoot\fi}%
+        \unvbox\z@\box\ifvoid\LT@lastfoot\LT@foot\else\LT@lastfoot\fi
 %    \end{macrocode}
 % End of "\ifnum\outputpenalty > -\LT@end@pen".
 %    \begin{macrocode}
diff --git a/Master/texmf-dist/source/latex-dev/tools/longtable.ins b/Master/texmf-dist/source/latex-dev/tools/longtable.ins
index 7ada121ea95..92a04e00d4e 100644
--- a/Master/texmf-dist/source/latex-dev/tools/longtable.ins
+++ b/Master/texmf-dist/source/latex-dev/tools/longtable.ins
@@ -3,8 +3,8 @@
 %% driver files from the doc files in this package when run through
 %% LaTeX or TeX.
 %%
-%% Copyright (C) 1993-2020
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% Copyright (C) 1993-2021
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the Standard LaTeX `Tools Bundle'.
@@ -45,8 +45,8 @@ The source is maintained by the LaTeX Project team and bug
 reports for it can be opened at https://latex-project.org/bugs/
 (but please observe conditions on bug reports sent to that address!)
 
-Copyright (C) 1993-2020
-The LaTeX3 Project and any individual authors listed elsewhere
+Copyright (C) 1993-2021
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/multicol.dtx b/Master/texmf-dist/source/latex-dev/tools/multicol.dtx
index 39bccef2d78..1d16a01c158 100644
--- a/Master/texmf-dist/source/latex-dev/tools/multicol.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/multicol.dtx
@@ -77,7 +77,7 @@
 %% not for the payment of a license fee per se (which might or might
 %% not follow from this evaluation).
 %%
-%% The license fee, if any, can be payed either to the LaTeX3 fund
+%% The license fee, if any, can be payed either to the LaTeX fund
 %% (see ltx3info.txt in the base LaTeX distribution) or to the author of
 %% the program who can be contacted at
 %%
diff --git a/Master/texmf-dist/source/latex-dev/tools/multicol.ins b/Master/texmf-dist/source/latex-dev/tools/multicol.ins
index f872b83cdee..c8838f8be22 100644
--- a/Master/texmf-dist/source/latex-dev/tools/multicol.ins
+++ b/Master/texmf-dist/source/latex-dev/tools/multicol.ins
@@ -3,8 +3,8 @@
 %% driver files from the doc files in this package when run through
 %% LaTeX or TeX.
 %%
-%% Copyright (C) 1993-2020
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% Copyright (C) 1993-2021
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the Standard LaTeX `Tools Bundle'.
@@ -45,8 +45,8 @@ The source is maintained by the LaTeX Project team and bug
 reports for it can be opened at https://latex-project.org/bugs/
 (but please observe conditions on bug reports sent to that address!)
 
-Copyright (C) 1993-2020
-The LaTeX3 Project and any individual authors listed elsewhere
+Copyright (C) 1993-2021
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/rawfonts.dtx b/Master/texmf-dist/source/latex-dev/tools/rawfonts.dtx
index 9c5daa57a50..f54aeaf44db 100644
--- a/Master/texmf-dist/source/latex-dev/tools/rawfonts.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/rawfonts.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/shellesc.dtx b/Master/texmf-dist/source/latex-dev/tools/shellesc.dtx
index 3b96c3e9ee3..54027cada76 100644
--- a/Master/texmf-dist/source/latex-dev/tools/shellesc.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/shellesc.dtx
@@ -1,8 +1,8 @@
 % \iffalse
 %% Source File: shellesc.dtx
-%% Copyright (C) 2015-2020
+%% Copyright (C) 2015-2021
 %%
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file may be distributed under the terms of the LPPL.
@@ -36,7 +36,7 @@
 % \title{The \textsf{shellesc} Package\thanks{This file
 %        has version number \fileversion, last
 %        revised \filedate.}}
-% \author{\LaTeX3 project}
+% \author{\LaTeX\ project}
 % \date{\filedate}
 %
 %
diff --git a/Master/texmf-dist/source/latex-dev/tools/showkeys.dtx b/Master/texmf-dist/source/latex-dev/tools/showkeys.dtx
index 59eb699ae81..3c9236f2ef4 100644
--- a/Master/texmf-dist/source/latex-dev/tools/showkeys.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/showkeys.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
@@ -22,7 +22,7 @@
 % \fi
 % \iffalse
 %% File: showkeys.dtx Copyright (C) 1992-1997 David Carlisle
-%% File: showkeys.dtx Copyright (C) 2006-2019 David Carlisle, LaTeX3 Project
+%% File: showkeys.dtx Copyright (C) 2006-2019 David Carlisle, LaTeX Project
 %
 %<*dtx>
           \ProvidesFile{showkeys.dtx}
diff --git a/Master/texmf-dist/source/latex-dev/tools/somedefs.dtx b/Master/texmf-dist/source/latex-dev/tools/somedefs.dtx
index 120ad980781..825a93ec666 100644
--- a/Master/texmf-dist/source/latex-dev/tools/somedefs.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/somedefs.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/tabularx.dtx b/Master/texmf-dist/source/latex-dev/tools/tabularx.dtx
index 577730e665b..a0f75fc4fa6 100644
--- a/Master/texmf-dist/source/latex-dev/tools/tabularx.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/tabularx.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/tabularx.ins b/Master/texmf-dist/source/latex-dev/tools/tabularx.ins
index 05effd3342e..a0d39c2564a 100644
--- a/Master/texmf-dist/source/latex-dev/tools/tabularx.ins
+++ b/Master/texmf-dist/source/latex-dev/tools/tabularx.ins
@@ -3,8 +3,8 @@
 %% driver files from the doc files in this package when run through
 %% LaTeX or TeX.
 %%
-%% Copyright (C) 1993-2020
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% Copyright (C) 1993-2021
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the Standard LaTeX `Tools Bundle'.
@@ -45,8 +45,8 @@ The source is maintained by the LaTeX Project team and bug
 reports for it can be opened at https://latex-project.org/bugs/
 (but please observe conditions on bug reports sent to that address!)
 
-Copyright (C) 1993-2020
-The LaTeX3 Project and any individual authors listed elsewhere
+Copyright (C) 1993-2021
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/theorem.dtx b/Master/texmf-dist/source/latex-dev/tools/theorem.dtx
index 0df7dbb7649..8543ff9d7cb 100644
--- a/Master/texmf-dist/source/latex-dev/tools/theorem.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/theorem.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/tools.ins b/Master/texmf-dist/source/latex-dev/tools/tools.ins
index 5e978712215..15c64ac80ab 100644
--- a/Master/texmf-dist/source/latex-dev/tools/tools.ins
+++ b/Master/texmf-dist/source/latex-dev/tools/tools.ins
@@ -3,8 +3,8 @@
 %% driver files from the doc files in this package when run through
 %% LaTeX or TeX.
 %%
-%% Copyright (C) 1993-2020
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% Copyright (C) 1993-2021
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the Standard LaTeX `Tools Bundle'.
@@ -49,8 +49,8 @@ reports for it can be opened at https://latex-project.org/bugs/
 (but please observe conditions on bug reports sent to that address!)
 
 
-Copyright (C) 1993-2020
-The LaTeX3 Project and any individual authors listed elsewhere
+Copyright (C) 1993-2021
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/trace.dtx b/Master/texmf-dist/source/latex-dev/tools/trace.dtx
index 4a08f569bb5..7ab6e18e25b 100644
--- a/Master/texmf-dist/source/latex-dev/tools/trace.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/trace.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/varioref.dtx b/Master/texmf-dist/source/latex-dev/tools/varioref.dtx
index 2bba60465e0..eac06580e73 100644
--- a/Master/texmf-dist/source/latex-dev/tools/varioref.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/varioref.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/varioref.ins b/Master/texmf-dist/source/latex-dev/tools/varioref.ins
index 951eedad891..559f1f28542 100644
--- a/Master/texmf-dist/source/latex-dev/tools/varioref.ins
+++ b/Master/texmf-dist/source/latex-dev/tools/varioref.ins
@@ -3,8 +3,8 @@
 %% driver files from the doc files in this package when run through
 %% LaTeX or TeX.
 %%
-%% Copyright (C) 1993-2020
-%% The LaTeX3 Project and any individual authors listed elsewhere
+%% Copyright (C) 1993-2021
+%% The LaTeX Project and any individual authors listed elsewhere
 %% in this file.
 %%
 %% This file is part of the Standard LaTeX `Tools Bundle'.
@@ -45,8 +45,8 @@ The source is maintained by the LaTeX Project team and bug
 reports for it can be opened at https://latex-project.org/bugs/
 (but please observe conditions on bug reports sent to that address!)
 
-Copyright (C) 1993-2020
-The LaTeX3 Project and any individual authors listed elsewhere
+Copyright (C) 1993-2021
+The LaTeX Project and any individual authors listed elsewhere
 in this file.
 
 This file was generated from file(s) of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/verbatim.dtx b/Master/texmf-dist/source/latex-dev/tools/verbatim.dtx
index e62886e0033..fcbaf28172e 100644
--- a/Master/texmf-dist/source/latex-dev/tools/verbatim.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/verbatim.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/xr.dtx b/Master/texmf-dist/source/latex-dev/tools/xr.dtx
index a963886cde7..c0d0b90c0fc 100644
--- a/Master/texmf-dist/source/latex-dev/tools/xr.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/xr.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.
diff --git a/Master/texmf-dist/source/latex-dev/tools/xspace.dtx b/Master/texmf-dist/source/latex-dev/tools/xspace.dtx
index ebe8d0f9478..adcfe154da3 100644
--- a/Master/texmf-dist/source/latex-dev/tools/xspace.dtx
+++ b/Master/texmf-dist/source/latex-dev/tools/xspace.dtx
@@ -1,8 +1,8 @@
 % \iffalse meta-comment
 %
-% Copyright (C) 1993-2020
+% Copyright (C) 1993-2021
 %
-% The LaTeX3 Project and any individual authors listed elsewhere
+% The LaTeX Project and any individual authors listed elsewhere
 % in this file.
 %
 % This file is part of the Standard LaTeX `Tools Bundle'.