witharrows (25jul19)

git-svn-id: svn://tug.org/texlive/trunk@51728 c570f23f-e606-0410-a88d-b1316a301751

1 files changed, 727 insertions, 255 deletions

diff --git a/Master/texmf-dist/source/latex/witharrows/witharrows.dtx b/Master/texmf-dist/source/latex/witharrows/witharrows.dtx
index c9b463ca716..f814d93b32b 100644
--- a/Master/texmf-dist/source/latex/witharrows/witharrows.dtx
+++ b/Master/texmf-dist/source/latex/witharrows/witharrows.dtx
@@ -15,8 +15,8 @@
 %
 % \fi
 % \iffalse
-\def\myfileversion{1.17}
-\def\myfiledate{2019/07/09}
+\def\myfileversion{1.18}
+\def\myfiledate{2019/07/24}
 %
 %
 %<*batchfile>
@@ -44,11 +44,11 @@ version 2005/12/01 or later.
 \endgroup
 %</batchfile>
 %
-%<@@=wa>
+%<@@=wi>
 %<*driver>
 \documentclass[dvipsnames]{l3doc}% dvipsnames is for xcolor (loaded by Tikz, loaded by witharrows)
 \usepackage{xltxtra}
-\usepackage{geometry}
+\usepackage[xetex]{geometry}
 \geometry{left=2.8cm,right=2.8cm,top=2.5cm,bottom=2.5cm,papersize={21cm,29.7cm}}
 \usepackage[footnotehyper]{witharrows}
 \usetikzlibrary{calc}
@@ -61,6 +61,7 @@ version 2005/12/01 or later.
 \def\emphase{\bgroup\color{RoyalPurple}\let\next=}
 \fvset{commandchars=\~\#\@,formatcom={\color{gray}}}
 \DeclareMathOperator{\re}{Re}
+\skip \footins = 2 \bigskipamount
 \parindent 0pt
 \DisableCrossrefs
 \begin{document}
@@ -75,6 +76,15 @@ version 2005/12/01 or later.
 %
 % \maketitle
 %
+% \hypersetup{
+%   pdfinfo = {
+%      Title = { The extension 'witharrows' },
+%      Subject = { A LaTeX extension } ,
+%      Author = { F. Pantigny }
+%   }
+% }
+%
+%
 % \begin{abstract}
 % The LaTeX package \pkg{witharrows} provides environments |{WithArrows}| and
 % |{DispWithArrows}| similar to the environments |{aligned}| and |{align}| of
@@ -98,7 +108,7 @@ version 2005/12/01 or later.
 % \begin{Verbatim}
 % $\begin{WithArrows}
 % A & = (a+1)^2 ~emphase#\Arrow{we expand}@ \\
-%   & = a^2 + 2a + 1  
+%   & = a^2 + 2a + 1  % don't put \\ here
 % \end{WithArrows}$
 % \end{Verbatim}
 %
@@ -117,9 +127,9 @@ version 2005/12/01 or later.
 %
 % \medskip
 % The environment |{WithArrows}| bears similarities with the environment
-% |{aligned}| of |amsmath| (and |mathtools|). The extension \pkg{witharrows}
+% |{aligned}| of \pkg{amsmath} (and |mathtools|). The extension \pkg{witharrows}
 % also provides an environment |{DispWithArrows}| which is similar to the
-% environment |{align}| of |amsmath|: cf. p. \pageref{DispWithArrows}.
+% environment |{align}| of \pkg{amsmath}: cf. p. \pageref{DispWithArrows}.
 % 
 %
 % \section{Options for the shape of the arrows}
@@ -164,7 +174,7 @@ version 2005/12/01 or later.
 % \end{WithArrows}$
 %
 % \interitem
-% The option |xoffset| shifts the arrows to the right (we usually don't want the
+% The option |xoffset| shifts the arrow to the right (we usually don't want the
 % arrows to be stucked on the text). The default value of |xoffset| is $3$~mm.
 % \begin{Verbatim}
 % $\begin{WithArrows}
@@ -217,7 +227,7 @@ version 2005/12/01 or later.
 %
 % \interitem
 % It's also possible to suppress both tips of the arrow with the Tikz option
-% |-|.
+% ``|-|''.
 % \begin{Verbatim}
 % $\begin{WithArrows}
 % A & = (a+1)^2 \Arrow[~emphase#tikz=-@]{very classical} \\
@@ -247,7 +257,7 @@ version 2005/12/01 or later.
 %
 % \smallskip 
 % In fact, it's possible to change more drastically the shape or the arrows with
-% the option |tikz-code| (presented p.~\pageref{tikz-code}.
+% the option |tikz-code| (presented p.~\pageref{tikz-code}).
 %
 % \interitem
 % It's possible to use the Tikz option ``|text width|'' to control the width of
@@ -323,16 +333,16 @@ version 2005/12/01 or later.
 %
 % \medskip
 % If we want exactly the same result as previously, we have to give to the
-% option |font| the value |{\itshape\small\bfseries}|.
+% option |font| the value |\itshape\small\bfseries|.
 %
 %
 % \interitem 
-% Almost all the options can be given directly between square brackets to the
-% environment |{WithArrows}|. \textbf{There must be no space before the opening
-% bracket (|[|) of the options of the environment.} The options apply to all the
-% arrows of the environment.\footnote{They also apply to the nested environments
-% |{WithArrows}| (with the logical exceptions of |interline|, |code-before| and
-% |code-after|).}
+% The options can be given directly between square brackets to the environment
+% |{WithArrows}|. There must be no space between the |\begin{WithArrows}| and
+% the opening bracket (|[|) of the options of the environment. Such options
+% apply to all the arrows of the environment.\footnote{They also apply to the
+% nested environments |{WithArrows}| (with the logical exceptions of
+% |interline|, |code-before| and |code-after|).}
 % %
 % \begin{Verbatim}
 % $\begin{WithArrows}[~emphase#tikz=blue@]
@@ -457,7 +467,7 @@ version 2005/12/01 or later.
 %
 %
 % \interitem 
-% The environment |{WithArrows}| gives also two options |code-before| and
+% The environment |{WithArrows}| provides also two options |code-before| and
 % |code-after|\footnote{For historical reasons, there are aliases for these
 % options: |CodeBefore| and |CodeAfter|.} for LaTeX code that will be executed
 % at the beginning and at the end of the environment. These options are not
@@ -519,9 +529,9 @@ version 2005/12/01 or later.
 % k & \;\le\; & t & \;\le\; & k+1 \\
 % \frac{1}{k+1} & \le & \frac{1}{t} & \le & \frac{1}{k} 
 % \Arrow{we can integrate the inequalities since $k \leq k+1$ } \\
-% \int\limits_k^{k+1} \frac{\text{d} t}{k+1} 
-% & \le & \int\limits_k^{k+1} \frac{\text{d} t}{t} 
-% & \le & \int\limits_k^{k+1} \frac{\text{d} t}{k} \\
+% \int\limits_k^{k+1} \frac{d t}{k+1} 
+% & \le & \int\limits_k^{k+1} \frac{dt}{t} 
+% & \le & \int\limits_k^{k+1} \frac{dt}{k} \\
 % \frac{1}{k+1} & \le & \ln(k+1)-\ln(k) & \le & \frac{1}{k} 
 % \end{DispWithArrows*}
 % \end{Verbatim}
@@ -532,9 +542,9 @@ version 2005/12/01 or later.
 % k & \;\le\; & t & \;\le\; & k+1 \\
 % \frac{1}{k+1} & \le & \frac{1}{t} & \le & \frac{1}{k} 
 % \Arrow{we can integrate the inequalities since $k \leq k+1$ } \\
-% \int\limits_k^{k+1} \frac{\text{d} t}{k+1} 
-% & \le & \int\limits_k^{k+1} \frac{\text{d} t}{t} 
-% & \le & \int\limits_k^{k+1} \frac{\text{d} t}{k} \\
+% \int\limits_k^{k+1} \frac{d t}{k+1} 
+% & \le & \int\limits_k^{k+1} \frac{dt}{t} 
+% & \le & \int\limits_k^{k+1} \frac{dt}{k} \\
 % \frac{1}{k+1} & \le & \ln(k+1)-\ln(k) & \le & \frac{1}{k} 
 % \end{DispWithArrows*}
 % 
@@ -568,7 +578,7 @@ version 2005/12/01 or later.
 % on the right side of the array. These nodes will be called \emph{right nodes}.
 %
 % By default, the arrows use the right nodes. We will say that they are in |rr|
-% mode ($r$ for \emph{right}). These arrows are |vertical| (we will say that an
+% mode ($r$ for \emph{right}). These arrows are vertical (we will say that an
 % arrow is \emph{vertical} when its two ends have the same abscissa).
 %
 %
@@ -882,7 +892,7 @@ version 2005/12/01 or later.
 %
 % \smallskip
 % \begin{Verbatim}
-% On pose\enskip $~emphase#\left\{@
+% Let's set\enskip $~emphase#\left\{@
 % \begin{WithArrows}[~emphase#c@]
 % f(x) & = 3x^3+2x^2-x+4 
 % \Arrow[tikz=-]{both are polynoms}\\
@@ -892,7 +902,7 @@ version 2005/12/01 or later.
 % \end{Verbatim}
 %
 %
-% On pose\enskip $\left\{
+% Let's set\enskip $\left\{
 % \begin{WithArrows}[c]
 % f(x) & = 3x^3+2x^2-x+4 
 % \Arrow[tikz=-]{both are polynoms}\\
@@ -1197,7 +1207,8 @@ version 2005/12/01 or later.
 % nodes:
 % \begin{itemize}
 % \item the command |\WithArrowsLastEnv| gives the number of the last
-% environment of level~$0$;
+% environment of level~$0$ (\emph{i.e.} which is not included in another
+% environnment of the package \pkg{witharrows});
 %
 % \item a name can be given to a given environment with the option |name| and,
 % in this case, the nodes created in the environment will have aliases
@@ -1313,9 +1324,9 @@ version 2005/12/01 or later.
 % \label{DispWithArrows}
 % 
 % As previously said, the environment |{WithArrows}| bears similarities with the
-% environment |{aligned}| of |amsmath| (and |mathtools|). This extension also
+% environment |{aligned}| of \pkg{amsmath} (and |mathtools|). This extension also
 % provides an environment |{DispWithArrows}| which is similar to the
-% environments |{align}| and |{flalign}| of |amsmath|.
+% environments |{align}| and |{flalign}| of \pkg{amsmath}.
 %
 % \medskip
 % The environment |{DispWithArrows}| must be used \emph{outside} math mode. Like
@@ -1434,18 +1445,52 @@ version 2005/12/01 or later.
 % more space on the right of the equations for the arrows) while still centering
 % the classical equations.
 %
-% \bigskip
-% If the package \pkg{amsmath} is loaded, it's possible to use the environment
-% |{subequations}| and the command |\intertext| in the environments
-% |{DispWithArrows}| and |{DispWithArrows*}| (and even the |\intertext| of
-% \pkg{nccmath} if this package is loaded).
-%
+% \medskip
 % If the option |leqno| is used as a class option, the labels will be composed
 % on the left also for the environments |{DispWithArrows}| and
 % |{DispWithArrows*}|.\footnote{The package \pkg{amsmath} has an option |leqno|
 % but \pkg{witharrows}, of course, is not aware of that option: \pkg{witharrows}
 % only checks the option |leqno| of the document class.}
 %
+% \medskip
+% If the package \pkg{amsmath} is loaded, it's possible to use the command
+% |\intertext| in the environments |{DispWithArrows}|. It's also possible to use
+% the environment |{subequations}|. However, there is, for the environments
+% |{DispWithArrows}| an option |subequations| to encapsulate the environment in
+% an environment |{subequations}|.
+%
+% \medskip
+% In the following example, the key |{subequations}| is fixed by the command
+% |\WithArrowsOptions|. Each environment |{DispWithArrows}| will subnumerated
+% (in the scope of the |\WithArrowsOptions|)
+% \begin{Verbatim}
+% ~emphase#\WithArrowsOptions{subequations}@
+% First environment.
+% \begin{DispWithArrows}
+% A & = B \\
+%   & = C 
+% \end{DispWithArrows}
+% Second environment.
+% \begin{DispWithArrows}
+% D & = E \\
+%   & = F 
+% \end{DispWithArrows}
+% \end{Verbatim}
+% %
+% \begin{scope}
+% \WithArrowsOptions{subequations}
+% First environment.
+% \begin{DispWithArrows}
+% A & = B \\
+%   & = C 
+% \end{DispWithArrows}
+% Second environment.
+% \begin{DispWithArrows}
+% D & = E \\
+%   & = F 
+% \end{DispWithArrows}
+% \end{scope}
+%
 % \bigskip
 % If there is not enough space to put the tag at the end of a line, there is no
 % automatic positioning of the label on the next line (as in the environments of
@@ -1591,9 +1636,84 @@ version 2005/12/01 or later.
 % It is not compatible with \pkg{showkeys} (not all the labels are shown).
 %
 % 
-% \section{Advanced features}
 %
 %
+% \subsection{The option <...> of DispWithArrows}
+%
+% The environment |{DispWithArrows}| provides an option |left-brace|. When present,
+% the value of this option is composed on the left, followed by a curly brace
+% (hence the name) and the body of the environment.\footnote{The option
+% |left-brace| can also be used without value: in this case, only the brace is drawn...}
+%
+% For lisibility, this option |left-brace| is also available with a special
+% syntax: it's possible to give this option between angle brackets  
+% (\verb|<| and \verb|>|) just after \verb|{DispWithArrows}| (before the optional
+% arguments between square brackets).
+%
+% \bigskip 
+% The following code is an example of multi-case equations.\footnote{The
+% environment |{cases}| of \pkg{amsmath} is a way to compose such multi-cases
+% equations. However, it's not possible to use the automatic numbering of
+% equations with this environment. The environment |{numcases}| of the extension
+% \pkg{cases} (written by Donald Arseneau) provides this possibility but, of
+% course, it's not possible to draw arrows with this extension.}
+%
+% \medskip
+%
+% \begin{BVerbatim}
+% \begin{DispWithArrows}~emphase#< \binom{n}{p} = >@[format = ll,fleqn,displaystyle]
+% 0 & \quad \text{if } p > n  
+% \Arrow{if fact, it's a special case\\ of the following one} \\
+% \frac{n(n-1)\cdots(n-p+1)}{p!} & \quad \text{if } 0 \leq p \leq n  \\
+% 0 & \quad \text{if } p < 0 
+% \end{DispWithArrows}
+% \end{BVerbatim}
+% %
+% \begin{DispWithArrows}< \binom{n}{p} = >[format = ll,fleqn,displaystyle]
+% 0 & \quad \text{if } p > n  
+% \Arrow{if fact, it's a special case\\ of the following one} \\
+% \frac{n(n-1)\cdots(n-p+1)}{p!} & \quad \text{if } 0 \leq p \leq n  \\
+% 0 & \quad \text{if } p < 0 
+% \end{DispWithArrows}
+%
+% \interitem
+% It's possible to use the environment |{subequations}| of \pkg{amsmath}. 
+%
+% \begin{Verbatim}
+% \begin{subequations}
+% \label{system}
+% \begin{DispWithArrows}<  (\ref*{system}) \Leftrightarrow >[format = l]
+% x+y+z = -3 \Arrow[tikz=-,jump=2]{3 equations} \\
+% xy+xz+yz=-2 \\
+% xyz = -15 \label{last-equation}
+% \end{DispWithArrows}
+% \end{subequations}
+% \end{Verbatim}
+% %
+% \begin{subequations}
+% \label{system}
+% \begin{DispWithArrows}< (\ref*{system}) \Leftrightarrow >[format = l]
+% x+y+z = -3 \Arrow[tikz=-,jump=2]{3 equations} \\
+% xy+xz+yz=-2 \\
+% xyz = -15 \label{last-equation} 
+% \end{DispWithArrows}
+% \end{subequations}
+%
+% \bigskip
+% The whole system is the equation \eqref{system} (this reference has been coded
+% by |\eqref{system}|) whereas the last equation is the equation
+% \eqref{last-equation} (this reference has been coded by
+% |\eqref{last-equation}|). The command |\ref*| used in the code above is
+% provided by \pkg{hyperref}. It's a variant of |\ref| which doesn't create 
+% interactive link.
+%
+% \bigskip
+% With the option \verb|replace-curly-brace-by|, it's possible to replace the
+% left curly brace can be replaced by another extensible delimiter.
+% 
+% \bigskip
+% \section{Advanced features}
+%
 % \subsection{The option tikz-code : how to change the shape of the arrows}
 %
 % \label{tikz-code}
@@ -1869,9 +1989,12 @@ version 2005/12/01 or later.
 %
 % \subsection{\textbackslash MoveEqLeft}
 %
-% It's possible to use |\MoveEqLeft| of \pkg{mathtools} (if we don't want
-% ampersand on the first line):
-% %
+% It's possible to use |\MoveEqLeft| of \pkg{mathtools}. Don't forget that
+% |\MoveEqLeft| has also the value of an ampersand (|&|). That's important for the
+% placement of an eventual command |\Arrow|.
+% 
+% 
+% 
 % \begin{Verbatim}[formatcom=\small\color{gray}]
 % $\begin{WithArrows}[interline=0.5ex]
 % ~emphase#\MoveEqLeft@ \arccos(x) = \arcsin \frac45 + \arcsin \frac5{13} 
@@ -2262,6 +2385,11 @@ version 2005/12/01 or later.
 \cs_new_protected:Npn \@@_msg_new:nnn { \msg_new:nnnn { witharrows } }
 \cs_new_protected:Npn \@@_msg_redirect_name:nn 
   { \msg_redirect_name:nnn { witharrows } }
+\cs_new_protected:Npn \@@_error:n { \msg_error:nn { witharrows } }
+\cs_new_protected:Npn \@@_warning:n { \msg_error:nn { witharrows } }
+\cs_new_protected:Npn \@@_fatal:n { \msg_fatal:nn { witharrows } }
+\cs_new_protected:Npn \@@_error:nn  { \msg_error:nnn { witharrows } }
+\cs_generate_variant:Nn \@@_error:nn { n x }
 %    \end{macrocode}
 % 
 % \medskip
@@ -2272,7 +2400,7 @@ version 2005/12/01 or later.
     footnote .bool_gset:N = \g_@@_footnote_bool ,
     footnotehyper .bool_gset:N = \g_@@_footnotehyper_bool ,
     unknown .code:n = 
-      \msg_fatal:nn { witharrows } { Option~unknown~for~package } 
+      \@@_fatal:n { Option~unknown~for~package } 
   }
 %    \end{macrocode}
 %
@@ -2298,7 +2426,7 @@ version 2005/12/01 or later.
 \@@_msg_new:nn { Option~incompatible~with~Beamer }
   { 
     The~option~'\l_keys_key_tl'\ is~incompatible~
-    with~Beamer~because~Beamer~has~its~own~system~to~extract~footnotes. 
+    with~Beamer~because~Beamer~has~its~own~system~to~extract~footnotes.
   }
 %    \end{macrocode}
 %
@@ -2309,7 +2437,8 @@ version 2005/12/01 or later.
     footnotehyper~has~already~been~loaded.~
     If~you~want,~you~can~use~the~option~'footnotehyper'~and~the~footnotes~  
     within~the~environments~of~witharrows~will~be~extracted~with~the~tools~
-    of~the~package~footnotehyper. 
+    of~the~package~footnotehyper.\\
+    If~you~go~on,~the~package~footnote~won't~be~loaded.
   }
 %    \end{macrocode}
 %
@@ -2320,7 +2449,8 @@ version 2005/12/01 or later.
     footnote~has~already~been~loaded.~
     If~you~want,~you~can~use~the~option~'footnote'~and~the~footnotes~  
     within~the~environments~of~witharrows~will~be~extracted~with~the~tools~
-    of~the~package~footnote. 
+    of~the~package~footnote.\\ 
+    If~you~go~on,~the~package~footnotehyper~won't~be~loaded.
   }
 %    \end{macrocode}
 %
@@ -2329,12 +2459,12 @@ version 2005/12/01 or later.
 \bool_if:NT \g_@@_footnote_bool 
   { 
     \@ifclassloaded { beamer }
-      { \msg_fatal:nn { witharrows } { Option~incompatible~with~Beamer } }
-      { }
-    \@ifpackageloaded { footnotehyper }
-      { \msg_fatal:nn { witharrows } { footnote~with~footnotehyper~package } }
-      { }
-    \usepackage { footnote } 
+      { \msg_info:nn { witharrows } { Option~incompatible~with~Beamer } }
+      { 
+        \@ifpackageloaded { footnotehyper }
+          { \@@_error:n { footnote~with~footnotehyper~package } }
+          { \usepackage { footnote } }
+      }
   }
 %    \end{macrocode}
 %
@@ -2342,12 +2472,12 @@ version 2005/12/01 or later.
 \bool_if:NT \g_@@_footnotehyper_bool 
   { 
     \@ifclassloaded { beamer }
-      { \msg_fatal:nn { witharrows } { Option~incompatible~with~Beamer } }
-      { }
-    \@ifpackageloaded { footnote }
-      { \msg_fatal:nn { witharrows } { footnotehyper~with~footnote~package } }
-      { }
-    \usepackage { footnotehyper }
+      { \@@_info:n  { Option~incompatible~with~Beamer } }
+      { 
+        \@ifpackageloaded { footnote }
+          { \@@_error:n { footnotehyper~with~footnote~package } }
+          { \usepackage { footnotehyper } }
+      }
     \bool_gset_true:N \g_@@_footnote_bool 
   }
 %    \end{macrocode}
@@ -2380,11 +2510,6 @@ version 2005/12/01 or later.
 % \bigskip
 % \subsection{Some technical definitions}
 %
-%    \begin{macrocode}
-\cs_new_protected:Npn \@@_error:n { \msg_error:nn { witharrows } }
-\cs_new_protected:Npn \@@_error:nn  { \msg_error:nnn { witharrows } }
-\cs_generate_variant:Nn \@@_error:nn { n x }
-%    \end{macrocode}
 % 
 %    \begin{macrocode}
 \cs_generate_variant:Nn \tl_put_right:Nn { N v }
@@ -2403,7 +2528,7 @@ version 2005/12/01 or later.
     \clist_map_inline:nn
       { 
         amsmath, amsthm, autonum, cleveref, hyperref, mathtools, showlabels,
-        typedref, varwidth 
+        typedref, unicode-math, varwidth 
       }
       {
         \bool_new:c { c_@@_#1_loaded_bool }
@@ -2449,6 +2574,25 @@ version 2005/12/01 or later.
   }
 %    \end{macrocode}
 % 
+% \bigskip
+% The following command converts each item of a sequence from |tl| to |str|. It
+% will be used when creating list of keys (a key name is always a |str|).
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_convert_to_str_seq:N #1
+  {
+    \seq_clear:N \l_tmpa_seq
+    \seq_map_inline:Nn #1 
+      {
+        \seq_put_left:Nx \l_tmpa_seq { \tl_to_str:n { ##1 } }
+      }
+    \seq_set_eq:NN #1 \l_tmpa_seq
+  }
+\cs_new_protected:Npn \@@_set_seq_of_str_from_clist:Nn #1 #2
+  {
+    \seq_set_from_clist:Nn #1 { #2 }
+    \@@_convert_to_str_seq:N #1
+  }
+%    \end{macrocode}
 % 
 % \bigskip
 % The command |\@@_save:N| saves a \pkg{expl3} variable by creating a global
@@ -2574,6 +2718,21 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 % \bigskip
+% The option |subequations| is an option which uses the environment
+% |{subequations}| of \pkg{amsmath}. That's why, if \pkg{amsmath} is loaded, we
+% add the key |subequations| to the list of the keys available in
+% |\WithArrowsOptions| and |{DispWithArrows}|.
+%    \begin{macrocode}
+\AtBeginDocument 
+  {
+    \bool_if:NTF \c_@@_amsmath_loaded_bool
+      {
+        \seq_put_right:Nn \l_@@_options_WithArrowsOptions_seq { subequations }
+        \seq_put_right:Nn \l_@@_options_DispWithArrows_seq { subequations }
+      }
+%    \end{macrocode}
+%
+% \bigskip
 % In order to increase the interline in the environments |{WithArrows}|,
 % |{DispWithArrows}|, etc., we will use the command |\spread@equation| of
 % \pkg{amsmath}. When used, this command becomes no-op (in the current TeX
@@ -2585,11 +2744,8 @@ version 2005/12/01 or later.
 % \pkg{amsmath} is not loaded (we put the code in a |\AtBeginDocument| because
 % the flag |\c_@@_amsmath_loaded_bool| is itself set in a |\AtBeginDocument|).
 %    \begin{macrocode}
-\AtBeginDocument 
-  {
-    \bool_if:NF \c_@@_amsmath_loaded_bool
       { 
-        \cs_set_protected:Npn \spread@equation
+        \cs_new_protected:Npn \spread@equation
           { 
             \openup \jot   
             \cs_set_eq:NN \spread@equation \prg_do_nothing:
@@ -2599,12 +2755,9 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 % \bigskip
-% For the construction of the preambles of the environments |{WithArrows}| and
-% |{DispWithArrows}|, we will have to insert the token |#| (catcode 6). We put it
-% in a \emph{toks register} of TeX (with no equivalent in \pkg{expl3}).
 %    \begin{macrocode}
-\newtoks \@@_parameter_token
-\@@_parameter_token = { # } 
+\tl_new:N \l_@@_left_brace_tl
+\tl_set_eq:NN \l_@@_left_brace_tl \c_novalue_tl
 %    \end{macrocode}
 %
 % \bigskip
@@ -2679,6 +2832,7 @@ version 2005/12/01 or later.
 % \item |\g_@@_col_int| to count the column of the |\halign|.
 % \end{itemize}
 %
+%
 % These counters will be incremented in a cell of the |\halign| and, therefore,
 % the incrementation must be global. However, we want to be able to include a
 % |{WithArrows}| in another |{WithArrows}|. To do so, we must restore the
@@ -2769,8 +2923,7 @@ version 2005/12/01 or later.
 \bool_new:N \l_@@_final_r_bool
 \tl_new:N \l_@@_initial_tl
 \tl_new:N \l_@@_final_tl
-\int_new:N \l_@@_nb_of_columns_int
-\bool_new:N \l_@@_last_col_bool
+\int_new:N \l_@@_nb_cols_int
 %    \end{macrocode}
 % 
 % \bigskip
@@ -2782,7 +2935,12 @@ version 2005/12/01 or later.
 \str_new:N \l_@@_format_str
 %    \end{macrocode}
 % 
-%
+% \bigskip
+% The option boolean corresponds to the option |subequations|.
+%    \begin{macrocode}
+\bool_new:N \l_@@_subequations_bool
+%    \end{macrocode}
+% 
 % \bigskip
 % \subsection{The definition of the options}
 %
@@ -2904,11 +3062,7 @@ version 2005/12/01 or later.
     end-adjust .dim_set:N = \l_@@_end_adjust_dim ,
     end-adjust .value_required:n = true ,
     end-adjust .initial:n = 0.4 ex ,
-    adjust .code:n  = 
-      \dim_zero_new:N \l_@@_start_adjust_dim
-      \dim_set:Nn \l_@@_start_adjust_dim { #1 }
-      \dim_zero_new:N \l_@@_end_adjust_dim
-      \dim_set:Nn \l_@@_end_adjust_dim { #1 } ,
+    adjust .meta:n  = { start-adjust = #1 , end-adjust = #1 } ,
     adjust .value_required:n = true ,
 %    \end{macrocode}
 %
@@ -2916,7 +3070,7 @@ version 2005/12/01 or later.
 % With the option |no-arrows|, the arrows won't be drawn. However, the ``first
 % pass'' of the arrows is done and some errors may be detected. The
 % nullification of |\@@_draw_arrows:nn| is for the standard arrows and the
-% nullification of |\@@_draw_arrow:nnn| is for ``Arrow in code-after''.
+% nullification of |\@@_draw_arrow:nnn| is for ``Arrow in |code-after|''.
 %    \begin{macrocode}
     no-arrows .code:n = 
       \cs_set_eq:NN \@@_draw_arrows:nn \use_none:nn
@@ -2942,6 +3096,26 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 % \bigskip
+% The following list of the (left) extensible delimiters of LaTeX is only for
+% the validation of the key |replace-left-brace-by|.
+%    \begin{macrocode}
+\clist_new:N \c_@@_extensible_delimiters_clist
+\clist_set:Nn \c_@@_extensible_delimiters_clist
+  { 
+    \{, (, [, \lbrace, \lbrack, \lgroup, \langle, \lmoustache, \lceil, \lfloor
+  }
+\AtBeginDocument
+  { 
+    \bool_if:nT 
+      { \c_@@_amsmath_loaded_bool || \use:c { c_@@_unicode-math_loaded_bool } } 
+      { 
+        \clist_put_right:Nn \c_@@_extensible_delimiters_clist { \lvert, \lVert }
+      }  
+  }
+%    \end{macrocode}
+%
+%
+% \bigskip
 % Now a set of keys specific to the environments |{DispWithArrows}| and
 % |{DispWithArrows*}| (and not |{WithArrows}|). Despite its name, this set of
 % keys will also be used in |\WithArrowsOptions|. 
@@ -2958,6 +3132,23 @@ version 2005/12/01 or later.
         { \clist_clear:N \l_@@_tags_clist }
         { \clist_set:Nn \l_@@_tags_clist { all } } ,
     notag .default:n = true ,
+%    \end{macrocode}
+% Since the option |subequations| is an option which insert the environment
+% |{DispWithArrows}| in an environment |{subequations}| of \pkg{amsmath}, we
+% must test whether the package \pkg{amsmath} is loaded. 
+%    \begin{macrocode}
+    subequations .code:n = 
+      \bool_if:NTF \c_@@_amsmath_loaded_bool
+        { \bool_set_true:N \l_@@_subequations_bool }
+        { 
+          \@@_error:n { amsmath~not~loaded } 
+          \group_begin:
+          \globaldefs = 1
+          \@@_msg_redirect_name:nn { amsmath~not~loaded } { info }
+          \group_end:
+        } ,
+    subequations .default:n = true ,
+    subequations .value_forbidden:n = true ,
     nonumber .meta:n = notag ,
     allow-multiple-labels .code:n = 
       \@@_msg_redirect_name:nn { Multiple~labels } { none } ,
@@ -2972,6 +3163,15 @@ version 2005/12/01 or later.
           \clist_put_left:Nn \l_@@_tags_clist \c_one_int
         } ,
     tagged-lines .value_required:n = true ,
+    replace-left-brace-by .code:n = 
+      {
+        \clist_if_in:NnTF 
+          \c_@@_extensible_delimiters_clist
+          { #1 }
+          { \tl_set:Nn \l_@@_replace_left_brace_by_tl { #1 } }
+          { \@@_error:n { Bad~value~for~replace~brace~by } }
+      } ,
+    replace-left-brace-by .initial:n = \lbrace ,
 %    \end{macrocode}
 %
 % Since the version 1.16 of \pkg{witharrows}, no vertical space is added between
@@ -2985,6 +3185,7 @@ version 2005/12/01 or later.
   }
 %    \end{macrocode}
 %
+%
 % \bigskip
 % Now a set of keys which will be used in all the environments (but not in
 % |\WithArrowsOptions}|). 
@@ -2993,10 +3194,15 @@ version 2005/12/01 or later.
 \keys_define:nn { WithArrows / Env } 
   { 
     name .code:n = 
-      \seq_if_in:NnTF \g_@@_names_seq { #1 }
+%    \end{macrocode}
+% First, we convert the value in a |str| because the list of the names will be a
+% list of |str|.
+%    \begin{macrocode}
+      \str_set:Nn \l_tmpa_str { #1 }
+      \seq_if_in:NVTF \g_@@_names_seq \l_tmpa_str
         { \@@_error:n { Duplicate~name } }
-        { \seq_gput_left:Nn \g_@@_names_seq { #1 } }
-      \str_set:Nn \l_@@_name_str { #1 } ,
+        { \seq_gput_left:NV \g_@@_names_seq \l_tmpa_str }
+      \str_set_eq:NN \l_@@_name_str \l_tmpa_str ,
     name .value_required:n = true ,
     code-before .code:n = \tl_put_right:Nn \l_@@_code_before_tl { #1 } ,
     code-before .value_required:n = true,
@@ -3004,34 +3210,21 @@ version 2005/12/01 or later.
     code-after .code:n = \tl_put_right:Nn \l_@@_code_after_tl { #1 } ,
     code-after .value_required:n = true ,
     CodeAfter  .meta:n = { code-after = #1 } ,
-    format .code:n = \@@_set_option_format:n { #1 },
+    format .code:n = 
+      \tl_if_empty:nTF { #1 } 
+        { \@@_error:n { Invalid~option~format } }
+        {
+          \regex_match:nnTF { \A[rcl]*\Z } { #1 }
+            { \tl_set:Nn \l_@@_format_str { #1 } }
+            { \@@_error:n { Invalid~option~format } }
+        } ,
     format .value_required:n = true ,
   }
 %    \end{macrocode}
 %
-% \medskip
-% An option |format| should contain only the letters |r|, |c| and |l|. That's
-% why we write a function to validate and set the value given to |format|.
-%    \begin{macrocode} 
-\cs_new_protected:Npn \@@_set_option_format:n #1
-  { 
-    \bool_set_true:N \l_tmpa_bool
-    \str_map_inline:nn { #1 }
-      {
-        \str_if_in:nnF {rcl} { ##1 }
-          { 
-            \bool_set_false:N \l_tmpa_bool
-            \@@_error:n { Invalid~option~format }
-            \str_map_break:
-          }
-      }
-    \bool_if:NT \l_tmpa_bool { \tl_set:Nn \l_@@_format_str { #1 } }
-  }
-%    \end{macrocode}
-%
 % 
 % \bigskip
-% Now, we begin the construction of the major sets of keys which are named
+% Now, we begin the construction of the major sets of keys, named
 % ``|WithArrows / WithArrows|'', ``|WithArrows / DispWithArrows|'' and 
 % ``|WithArrows / WithArrowsOptions|''. Each of these sets of keys will be
 % completed after.
@@ -3061,17 +3254,23 @@ version 2005/12/01 or later.
 % 
 % 
 % \bigskip
-% A sequence of the options available in |{WithArrows}|. This sequence will be
-% used in the error messages and can be modified dynamically.
+% A sequence of |str| for the options available in |{WithArrows}|. This sequence
+% will be used in the error messages and can be modified dynamically.
 %    \begin{macrocode}
 \seq_new:N \l_@@_options_WithArrows_seq
-\seq_set_from_clist:Nn \l_@@_options_WithArrows_seq
+\@@_set_seq_of_str_from_clist:Nn \l_@@_options_WithArrows_seq
   { 
-    adjust, b, c, code-after, code-before, command-name, displaystyle, end-adjust,
-    format, group, groups, i, interline, jot, ll, lr, more-columns, name,
-    no-arrows, rl, rr, show-node-names, show-nodes, start-adjust, t, tikz,
-    tikz-code, xoffset, ygap, ystart
+    adjust, b, c, code-after, code-before, command-name,
+    displaystyle, end-adjust, 
+    format, group, groups, i,
+    interline, jot, ll,
+    lr, more-columns, name, 
+    no-arrows, rl, rr, 
+    show-node-names, show-nodes, start-adjust,
+    t, tikz, tikz-code, 
+    xoffset, ygap, ystart 
   } 
+\@@_convert_to_str_seq:N \l_@@_options_WithArrows_seq
 %    \end{macrocode}
 %
 % \medskip
@@ -3088,6 +3287,7 @@ version 2005/12/01 or later.
 %    \begin{macrocode}
 \keys_define:nn { WithArrows / DispWithArrows } 
   { 
+    left-brace .tl_set:N = \l_@@_left_brace_tl ,
     unknown .code:n  = 
       \@@_sort_seq:N \l_@@_options_DispWithArrows_seq
       \@@_error:n { Unknown~option~DispWithArrows } 
@@ -3099,13 +3299,13 @@ version 2005/12/01 or later.
 % be used in the error messages and can be modified dynamically.
 %    \begin{macrocode}
 \seq_new:N \l_@@_options_DispWithArrows_seq
-\seq_set_from_clist:Nn \l_@@_options_DispWithArrows_seq
+\@@_set_seq_of_str_from_clist:Nn \l_@@_options_DispWithArrows_seq
   { 
     allow-multiple-labels, code-after, code-before, command-name, tikz-code, adjust,
     displaystyle, end-adjust, fleqn, group, format, groups, i, interline, jot,
-    ll, lr, mathindent, name, no-arrows, nonumber, notag, rl, rr,
-    show-node-names, show-nodes, start-adjust, tagged-lines, tikz, wrap-lines,
-    xoffset, ygap, ystart 
+    left-brace, ll, lr, mathindent, name, no-arrows, nonumber, notag, 
+    replace-left-brace-by, rl, rr, show-node-names, show-nodes, start-adjust, 
+    tagged-lines, tikz, wrap-lines, xoffset, ygap, ystart 
   }
 %    \end{macrocode}
 % 
@@ -3128,7 +3328,7 @@ version 2005/12/01 or later.
 % will be used in the error messages and can be modified dynamically.
 %    \begin{macrocode}
 \seq_new:N \l_@@_options_WithArrowsOptions_seq
-\seq_set_from_clist:Nn \l_@@_options_WithArrowsOptions_seq
+\@@_set_seq_of_str_from_clist:Nn \l_@@_options_WithArrowsOptions_seq
   { 
     allow-duplicate-names, allow-multiple-labels, b, c, command-name,
     more-columns, tikz-code, adjust, displaystyle, end-adjust, fleqn, group,
@@ -3151,7 +3351,7 @@ version 2005/12/01 or later.
       {
         \str_set_eq:NN \l_@@_previous_key_str \l_keys_key_tl
         \str_set:Nn \l_@@_status_arrow_str { independent } 
-        \str_if_eq:VnF \l_keys_value_tl { NoValue } 
+        \str_if_eq:VnF \l_keys_value_tl { NoValue }
           { \@@_error:n { Value~for~a~key } }
       }
       { \@@_error:n { Incompatible~options~in~Arrow } }
@@ -3219,6 +3419,12 @@ version 2005/12/01 or later.
     adjust .value_required:n = true ,
     unknown .code:n = 
       \@@_sort_seq:N \l_@@_options_Arrow_seq
+      \seq_if_in:NVTF \l_@@_options_WithArrows_seq \l_keys_key_tl
+        { 
+          \str_set:Nn \l_tmpa_str
+           { ~However,~this~key~can~be~used~in~the~options~of~\{WithArrows\}. } 
+        }
+        { \str_clear:N \l_tmpa_str }
       \@@_error:n { Unknown~option~in~Arrow }
   }
 %    \end{macrocode}
@@ -3229,7 +3435,7 @@ version 2005/12/01 or later.
 % the error messages and can be modified dynamically.
 %    \begin{macrocode}
 \seq_new:N \l_@@_options_Arrow_seq
-\seq_set_from_clist:Nn \l_@@_options_Arrow_seq
+\@@_set_seq_of_str_from_clist:Nn \l_@@_options_Arrow_seq
   { 
     adjust, end-adjust, i, jump, ll, lr, rl, rr, start-adjust, tikz, tikz-code,
     xoffset 
@@ -3485,6 +3691,23 @@ version 2005/12/01 or later.
     \seq_gput_right:NV \g_@@_col_int_seq \g_@@_col_int
     \int_gzero:N \g_@@_col_int 
 %    \end{macrocode}
+%
+% In the preamble of the |\halign|, there will be \emph{two} counters of the
+% columns. The aim of this programmation is to detect the utilisation of a
+% command |\omit| in a cell of the |\halign| (it should be forbidden).
+% For example, in the part of the preamble concerning the third column (if there
+% is a third column in the environment), we will have the following instructions :
+% \begin{Verbatim}
+%  \int_gincr:N \g_~@~@_col_int
+%  \int_gset:Nn \g_~@~@_static_col_int 3
+% \end{Verbatim}
+%  The counter |\g_@@_col_int| is incremented dynamically and the second is
+%  static. If the user has used a command |\omit|, the dynamic incrementation is
+%  not done in the cell and, at this end of the row, the difference between the
+%  counters may infer the presence of |\omit| at least once.
+%    \begin{macrocode}
+    \int_gzero_new:N \g_@@_static_col_int
+%    \end{macrocode}
 % 
 % \bigskip
 % We also have to update the position on the nesting tree.
@@ -3537,12 +3760,6 @@ version 2005/12/01 or later.
     \str_set:Nn \l_@@_format_str { rl }
 %    \end{macrocode}
 % 
-% \bigskip
-% The boolean |\l_@@_last_col_bool| will be used only during the construction of
-% the preamble (in |\@@_construct_halign:|).
-%    \begin{macrocode}
-    \bool_set_true:N \l_@@_last_col_bool
-%    \end{macrocode}
 %
 %
 % \bigskip
@@ -3599,17 +3816,33 @@ version 2005/12/01 or later.
 % command |\@@_Arrow:|.
 %
 % \medskip
-% The counter |\l_@@_nb_of_columns_int| is the number of columns in the
+% The counter |\l_@@_nb_cols_int| is the number of columns in the
 % |\halign| (excepted the column for the labels of equations in
-% |{DispWithArrows}| and excepted evenutals other columns in |{WithArrows}| if
-% the user uses the option |more-columns|).
+% |{DispWithArrows}| and excepted eventuals other columns in |{WithArrows}| allowed
+% by the option |more-columns|).
 %    \begin{macrocode}
-    \int_set:Nn \l_@@_nb_of_columns_int { \str_count:N \l_@@_format_str } 
+    \int_set:Nn \l_@@_nb_cols_int { \str_count:N \l_@@_format_str } 
 %    \end{macrocode}
+%   
+% \medskip
+% Be careful! The following counter |\g_@@_col_int| will be used for two usages:
+% \begin{itemize}
+% \item during, the construction of the preamble of the |\halign|, it will be
+% used as counter for the number of the column under construction in the
+% preamble (since the preamble is constructed backwards, |\g_@@_col_int| will go
+% decreasing from |\l_@@_nb_cols_int| to $1$) ;
+% \item once the preamble constructed, the primitive |\halign| is executed, and,
+% in each row of the |\halign|, the counter |\g_@@_col_int| will be increased
+% from column to column.
+% \end{itemize}
 %
+%    \begin{macrocode}
+    \int_gset_eq:NN \g_@@_col_int \l_@@_nb_cols_int
+%    \end{macrocode}
+% 
 % \medskip
-% We convert the format in a sequence because we use it as a stack in the
-% construction of the preamble.
+% We convert the format in a sequence because we use it as a stack (with the top
+% of the stack at the end of the sequence) in the construction of the preamble.
 %    \begin{macrocode}
     \seq_clear_new:N \l_@@_format_seq
     \seq_set_split:NnV \l_@@_format_seq { } \l_@@_format_str
@@ -3645,7 +3878,7 @@ version 2005/12/01 or later.
 %
 %    \begin{macrocode}
     \cs_set_eq:NN \notag \@@_notag:
-    \cs_set_eq:NN \nonumber \@@_notag:
+    \cs_set_eq:NN \nonumber \@@_nonumber:
     \cs_set_eq:NN \tag \@@_tag
     \cs_set_eq:NN \@@_old_label \label
     \cs_set_eq:NN \label \@@_label:n
@@ -3662,8 +3895,8 @@ version 2005/12/01 or later.
 % the last column (more precisely: except the part concerning the construction
 % of the left node and the right node).
 %
-% The same function |\@@_construct_halign:| will be used both for |{WithArrows}|
-% and |{DispWithArrows}|.
+% The same function |\@@_construct_halign:| will be used both for the
+% environment |{WithArrows}| and the environment |{DispWithArrows}|.
 % 
 % Several important points must be noted concerning that construction of the
 % preamble.
@@ -3678,6 +3911,9 @@ version 2005/12/01 or later.
 % expansion of the preamble gives the ability of controlling which parts of the
 % code will be expanded during the construction of the preamble (other parts
 % will be expanded and executed only during the execution of the |\halign|).
+% \item The counter |\g_@@_col_int| is used during the loop of the construction
+% of the preamble but, it will also appears in the preamble (we could have
+% chosen two differents counters but this way saves a counter).
 % \end{itemize}
 % 
 %    \begin{macrocode}
@@ -3693,17 +3929,17 @@ version 2005/12/01 or later.
         \use:x
           {
 %    \end{macrocode}
-% Before the recursive call of |\@@_construct_halign:|, 
-% we lower the flag |\l_@@_last_col_bool| in order that all the recursive calls
-% will know that they are not in the last column. But, during the construction
-% of the first column, it is \emph{not} lowered because |\bool_set_false:N|,
-% which is protected, won't be expanded by the |\use:x|.
+% Before the recursive call of |\@@_construct_halign:|, we decrease the integer
+% |\g_@@_col_bool|. But, during the construction of the column which is
+% constructed first (that is to say which is the last column of the |\halign|),
+% it is \emph{not} lowered because |\int_decr:N|, which is protected, won't be
+% expanded by the |\use:x|.
 %
 % We begin the construction of a generic column.
 %    \begin{macrocode}
-            \bool_set_false:N \l_@@_last_col_bool 
+            \int_gdecr:N \g_@@_col_int
             \@@_construct_halign:
-            \bool_if:NT \l_@@_last_col_bool 
+            \int_compare:nNnT \g_@@_col_int = \l_@@_nb_cols_int
               { 
 %    \end{macrocode}
 % We redefine the command |\Arrow| (or the name given to the corresponding
@@ -3732,19 +3968,20 @@ version 2005/12/01 or later.
             \str_if_eq:VnT \l_@@_type_col_str { c } \hfil
             \str_if_eq:VnT \l_@@_type_col_str { r } \hfill
             \int_gincr:N \g_@@_col_int
-            $ % $
+            \int_gset:Nn \g_@@_static_col_int { \int_use:N \g_@@_col_int }
+            \c_math_toggle_token
               {
                 { }
                 \bool_if:NT \l_@@_displaystyle_bool \displaystyle
                 ####
               }
-            $ % $
-            \bool_if:NTF \l_@@_last_col_bool
+            \c_math_toggle_token
+            \int_compare:nNnTF \g_@@_col_int = \l_@@_nb_cols_int
               { \@@_construct_nodes: }
               {
 %    \end{macrocode}
 % The following glue (|\hfil|) will be added only if we are not in the last cell
-% because, in the last cell, a glue is added beetween the nodes (in
+% because, in the last cell, a glue (=skip) is added between the nodes (in
 % |\@@_construct_nodes:|). 
 %    \begin{macrocode}
                 \str_if_eq:VnT \l_@@_type_col_str { l } \hfil
@@ -3765,14 +4002,18 @@ version 2005/12/01 or later.
             \bgroup
           }
           {
-            \halign to
-            \bool_if:NTF \l_@@_inlabel_bool \linewidth \displaywidth
+            \halign to \l_@@_linewidth_dim
             \bgroup
             \bool_if:NT \l_@@_fleqn_bool
               { \skip_horizontal:N \l_@@_mathindent_dim }
           }
         \int_gincr:N \g_@@_line_int 
         \int_gzero:N \g_@@_col_int
+        \tl_if_eq:NNF \l_@@_left_brace_tl \c_novalue_tl
+          {
+            \skip_horizontal:n 
+              { \box_wd:N \l_@@_left_brace_box + \l_@@_delim_wd_dim } 
+          }
         \strut
       }
   }
@@ -3781,8 +4022,8 @@ version 2005/12/01 or later.
 %
 % \bigskip
 % The command |\@@_construct_nodes:| is only for the lisibility of the code
-% because, in fact, it is used only once. It construct the ``left node'' and the
-% ``right node'' at the end of each row of the arrow.
+% because, in fact, it is used only once. It constructs the ``left node'' and
+% the ``right node'' at the end of each row of the arrow.
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_construct_nodes:
   { 
@@ -3838,7 +4079,6 @@ version 2005/12/01 or later.
 % \bigskip
 % \subsubsection{The environment \{WithArrows\}}
 %
-%
 % 
 %    \begin{macrocode}
 \NewDocumentEnvironment { WithArrows } { ! O { } }
@@ -3864,7 +4104,8 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 % \bigskip
-% We begin the |\halign| and the preamble.
+% We begin the |\halign| and the preamble. During the construction of the
+% preamble, |\l_tmpa_int| will be incremented during each column constructed.
 %    \begin{macrocode}
     \@@_construct_halign: 
 %    \end{macrocode}
@@ -3881,10 +4122,10 @@ version 2005/12/01 or later.
 %    \begin{macrocode}
     && 
     \@@_error:n { Too~much~columns~in~WithArrows }
-    $ 
+    \c_math_toggle_token
     \bool_if:NT \l_@@_displaystyle_bool \displaystyle 
     { ## } 
-    $
+    \c_math_toggle_token
     \cr
   }
 %    \end{macrocode}
@@ -4012,7 +4253,13 @@ version 2005/12/01 or later.
 \cs_new_protected:Npn \@@_cr:
   { 
     \scan_stop:
-    \prg_replicate:nn { \l_@@_nb_of_columns_int - \g_@@_col_int } { & { } } 
+%    \end{macrocode}
+% We try to detect some |\omit| (as of now, an |\omit| in the last column is
+% not detected).
+%    \begin{macrocode}
+    \int_compare:nNnF \g_@@_col_int = \g_@@_static_col_int
+      { \@@_error:n { omit~probably~used } }
+    \prg_replicate:nn { \l_@@_nb_cols_int - \g_@@_static_col_int } { & { } } 
     \group_align_safe_begin:
     \peek_meaning_remove:NTF * \@@_cr_i: \@@_cr_i:
   }
@@ -4027,15 +4274,36 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 % 
 % \bigskip
+% Now, we test if the next token is the token |\end|. Indeed, we want to test if
+% the following tokens are |\end{WithArrows}| (or |\end{DispWithArrows}|, etc).
+% In this case, we raise an error because the user must not put "\\" at the end
+% of its alignment.
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_cr_ii: [ #1 ]
   { 
+    \peek_meaning_ignore_spaces:NTF \end 
+      { 
+        \@@_cr_iii:n { #1 } 
+%    \end{macrocode}
+% The analyse of the argument of the token |\end| must be after the
+% |\group_align_safe_end:| which is the beginning of |\@@_cr_iii:n|.
+%    \begin{macrocode}
+        \@@_analyze_end:Nn 
+      }
+      { \@@_cr_iii:n { #1 } }
+  }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_cr_iii:n #1 
+  {
     \group_align_safe_end:
 %    \end{macrocode}
 % For the environment |{DispWithArrows}|, the behaviour of |\\| is different
-% because we add the third column which is the column for the tag (number of the
-% equation). Even if there is no tag, the third column is used for the
-% |v|-nodes.
+% because we add the last column which is the column for the tag (number of the
+% equation). Even if there is no tag, this column is used for the
+% |v|-nodes.\footnote{The |v|-nodes are used to compute the abscissa of the
+% right margin, used by the option |wrap-lines|.}
 %    \begin{macrocode}
     \bool_if:NT \l_@@_in_DispWithArrows_bool
 %    \end{macrocode}
@@ -4172,12 +4440,39 @@ version 2005/12/01 or later.
                \coordinate ( \int_use:N \g_@@_line_int - v ) ; 
           }
       }
-    \cr \noalign { \skip_vertical:n { #1 + \l_@@_interline_skip } \scan_stop: } 
+    \dim_compare:nNnT { #1 } < \c_zero_dim
+       { \@@_error:n { option~of~cr~negative } }
+    \dim_set:Nn \l_tmpa_dim { \dim_max:nn { #1 } \c_zero_dim }
+    \cr 
+    \noalign 
+      { 
+        \skip_vertical:n { \l_tmpa_dim + \l_@@_interline_skip }
+        \scan_stop: 
+      }  
   }
 %    \end{macrocode}
 % According to the documentation of \pkg{expl3}, the previous addition in 
 % ``|#1 + \l_@@_interline_skip|'' is really an addition of skips (=glues).
 %
+%
+% The following command will be used when, after a |\\| (and its optional
+% arguments) there is a |\end|. You want to known if this is the end of the
+% environment |{WithArrows}| (or |{DispWithArrows}|, etc.) because, in this
+% case, we will explain that the environment must not be ended by |\\|. If it is
+% not the case, that means it's a classical situation of LaTeX environments not
+% correctly imbricated and there will be a LaTeX error.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_analyze_end:Nn #1 #2
+  {
+    \exp_args:NV \str_if_eq:nnT \l_@@_type_env_str { #2 }
+      { \@@_warning:n { newline~at~the~end~of~env } }
+%    \end{macrocode}
+% We reput in the stream the |\end{...}| we have extracted.
+%    \begin{macrocode}
+    \end { #2 }
+  }
+%    \end{macrocode}
+%
 % \bigskip
 % \subsubsection{The environment \{DispWithArrows\}}
 %
@@ -4188,23 +4483,24 @@ version 2005/12/01 or later.
 % 
 % The purpose of the |\vtop| is to have an environment unbreakable.
 %
-% However, if we are juste after an item of a LaTeX list, the construction is
-% slightly different:
+% However, if we are juste after an item of a LaTeX list or at the beginning of
+% a |{minipage}|, the construction is slightly different:
 %
 % |\[\vtop{\halign to \linewidth {...}}\]|
 % 
 % 
 % \bigskip
-% The boolean |\l_@@_inlabel_bool| will be raised if we are just after a |\item|
-% of a list of LaTeX.
+% The boolean |\l_@@_in_label_or_minipage_bool| will be raised if we are just after a |\item|
+% of a list of LaTeX or at the beginning of a |{minipage}|.
 %    \begin{macrocode}
-\bool_new:N \l_@@_inlabel_bool
+\bool_new:N \l_@@_in_label_or_minipage_bool
 %    \end{macrocode}
 %
 % 
 %    \begin{macrocode}
-\NewDocumentEnvironment { DispWithArrows } { ! O { } }
+\NewDocumentEnvironment { DispWithArrows } { ! d < > ! O { } }
   { 
+    \bool_set_true:N \l_@@_in_DispWithArrows_bool
 %    \end{macrocode}
 % If \pkg{mathtools} has been loaded with the option |showonlyrefs|, we disable
 % the code of \pkg{mathtools} for the option |showonlyrefs| with the command
@@ -4237,23 +4533,58 @@ version 2005/12/01 or later.
 % definition of |\intertext|.
 %    \begin{macrocode}
     \bool_if:NT \c_@@_amsmath_loaded_bool \intertext@
-    \bool_set_true:N \l_@@_in_DispWithArrows_bool
-    \@@_pre_halign:n { #1 }
+    \IfValueT { #1 } { \tl_set:Nn \l_@@_left_brace_tl { #1 } }
+    \@@_pre_halign:n { #2 }
 %    \end{macrocode}
 %
+% If |subequations| is used, we encapsulate the environment in an
+% environment |{subequations}| of \pkg{amsmath}.
+%    \begin{macrocode}
+    \bool_if:NT \l_@@_subequations_bool { \begin { subequations } }
+%    \end{macrocode}
 % Since the version 1.16 of \pkg{witharrows}, no space is added between an
 % |\item| of a LaTeX list and an environment |{DispWithArrows}| except with the
 % option |standard-behaviour-with-items| stored in the boolean
 % |\l_@@_sbwi_bool|. We have to know if we are just after an |\item| and this
-% information will be stored in |\l_@@_inlabel_bool|.
+% information will be stored in |\l_@@_in_label_or_minipage_bool|.
 %    \begin{macrocode}
     \bool_if:NF \l_@@_sbwi_bool
       {  
         \if@inlabel
-        \bool_set_true:N \l_@@_inlabel_bool
+        \bool_set_true:N \l_@@_in_label_or_minipage_bool
+        \fi
+        \if@minipage
+        \bool_set_true:N \l_@@_in_label_or_minipage_bool
         \fi
       }
 %    \end{macrocode}
+%
+%
+%    \begin{macrocode}
+    \tl_if_eq:NNF \l_@@_left_brace_tl \c_novalue_tl
+      {
+        \hbox_set:Nn \l_tmpa_box 
+          { 
+            \c_math_toggle_token
+            \left \l_@@_replace_left_brace_by_tl \vcenter to 1 cm { } \right.
+            \c_math_toggle_token
+          }
+        \dim_zero_new:N \l_@@_delim_wd_dim
+        \dim_set:Nn \l_@@_delim_wd_dim { \box_wd:N \l_tmpa_box }
+        \box_clear_new:N \l_@@_left_brace_box
+        \hbox_set:Nn \l_@@_left_brace_box 
+          { 
+            \group_begin:
+              \cs_set_eq:NN \label \@@_old_label
+              \c_math_toggle_token
+              \bool_if:NT \l_@@_displaystyle_bool \displaystyle 
+              \l_@@_left_brace_tl
+              { } 
+              \c_math_toggle_token
+            \group_end:
+          }  
+      }
+%    \end{macrocode}
 % 
 % \bigskip
 % The token list |\l_@@_tag_tl| will contain the argument of the command |\tag|.
@@ -4275,17 +4606,17 @@ version 2005/12/01 or later.
 % 
 %    \begin{macrocode}
     \if_mode_math:
-      \@@_error:n { DispWithArrows~in~math~mode }
+      \@@_fatal:n { DispWithArrows~in~math~mode }
     \fi:
 %    \end{macrocode}
 %
 % \bigskip
 % The construction is not exactly the same whether we are just after an |\item|
 % of a LaTeX list or not. We know if we are after an |\item| thanks to the
-% boolean |\l_@@_inlabel_bool|.
+% boolean |\l_@@_in_label_or_minipage_bool|.
 %    \begin{macrocode}
-    \bool_if:NTF \l_@@_inlabel_bool
-      { $ } % $ 
+    \bool_if:NTF \l_@@_in_label_or_minipage_bool
+      { \c_math_toggle_token } 
       {  
 %    \end{macrocode}
 % We don't use |\[| of LaTeX because some extensions, like \pkg{autonum}, do a
@@ -4296,15 +4627,25 @@ version 2005/12/01 or later.
         \nointerlineskip
         \hbox_to_wd:nn { .6 \linewidth } { }
         \fi:
-        $$
+        \c_math_toggle_token \c_math_toggle_token
       }
 %    \end{macrocode}
-% We use a |\vtop| in order to prevent page breaks in the environment.
+%
+%    \begin{macrocode}
+    \dim_zero_new:N \l_@@_linewidth_dim
+    \bool_if:NTF \l_@@_in_label_or_minipage_bool 
+       { \dim_set_eq:NN \l_@@_linewidth_dim \linewidth }
+       { \dim_set_eq:NN \l_@@_linewidth_dim \displaywidth }
+%    \end{macrocode}
+%
+% 
 %    \begin{macrocode}
-    \vtop \bgroup 
-    \bool_if:NTF \l_@@_fleqn_bool
-      { \tabskip = \c_zero_skip }
-      { \tabskip = 0 pt plus 1000 pt minus 1000 pt }
+    \box_clear_new:N \l_@@_halign_box
+    \setbox \l_@@_halign_box \vtop \bgroup
+    \tabskip =
+      \bool_if:NTF \l_@@_fleqn_bool
+        \c_zero_skip 
+        { 0 pt plus 1000 pt minus 1000 pt }
 %    \end{macrocode}
 %
 %
@@ -4314,7 +4655,7 @@ version 2005/12/01 or later.
     & 
 %    \end{macrocode}
 %
-% If the user try to use more columns than the lenght of the format, we have to
+% If the user tries to use more columns than the length of the format, we have to
 % raise an error. However, the error won't be in the next column which is the
 % columns for the labels of the equations. The error will be after... and it
 % must be after. That means that we must not have an error in the next column
@@ -4324,7 +4665,7 @@ version 2005/12/01 or later.
     $ ## $
     \tabskip = \c_zero_skip
     && 
-    \@@_error:n { Too~much~columns~in~DispWithArrows } 
+    \@@_fatal:n { Too~much~columns~in~DispWithArrows } 
     \bool_if:nT \c_false_bool { ## }
     \cr
   }
@@ -4341,13 +4682,54 @@ version 2005/12/01 or later.
 % The following |\egroup| is for the |\halign|.
 %    \begin{macrocode}
     \egroup 
-%    \end{macrocode}
-% The following |\egroup| is for the |\vtop|.
+    \unskip \unpenalty \unskip \unpenalty 
+    \box_set_to_last:N \l_tmpa_box
+    \nointerlineskip 
+    \box_use:N \l_tmpa_box 
+    \dim_gzero_new:N \g_@@_alignment_dim
+    \dim_gset:Nn \g_@@_alignment_dim { \box_wd:N \l_tmpa_box }
+    \box_clear_new:N \l_@@_new_box
+    \hbox_set:Nn \l_@@_new_box { \hbox_unpack_clear:N \l_tmpa_box } 
+    \dim_compare:nNnT 
+      { \box_wd:N \l_@@_new_box } < \g_@@_alignment_dim
+      { \dim_gset:Nn \g_@@_alignment_dim { \box_wd:N \l_@@_new_box } }
+%    \end{macrocode}
+% The |\egroup| is for the box |\l_@@_halign_box|.
 %    \begin{macrocode}
-    \egroup 
+    \egroup
 %    \end{macrocode}
 %
-%
+%    \begin{macrocode}
+     \tl_if_eq:NNTF \l_@@_left_brace_tl \c_novalue_tl
+       { \box_use_drop:N \l_@@_halign_box }
+       { 
+         \hbox_to_wd:nn \l_@@_linewidth_dim
+           {
+            \bool_if:NTF \l_@@_fleqn_bool
+              { \skip_horizontal:n \l_@@_mathindent_dim }
+              \hfil
+            \hbox_to_wd:nn \g_@@_alignment_dim 
+              { 
+                \box_use_drop:N \l_@@_left_brace_box
+                \dim_set:Nn \l_tmpa_dim 
+                  { 
+                    \box_ht:N \l_@@_halign_box
+                    + \box_dp:N \l_@@_halign_box
+                  }
+                \c_math_toggle_token
+                  \left \l_@@_replace_left_brace_by_tl 
+                    \vcenter to \l_tmpa_dim { \vfil } 
+                  \right. 
+                \c_math_toggle_token
+                \hfil
+              }
+            \hfil
+           } 
+         \skip_horizontal:n { - \l_@@_linewidth_dim } 
+         \vcenter { \box_use_drop:N \l_@@_halign_box }
+       }
+%    \end{macrocode}
+% 
 % We compute the dimension |\g_@@_right_x_dim|. As a first approximation,
 % |\g_@@_right_x_dim| is the $x$-value of the right side of the current
 % composition box. In fact, we must take into account the potential labels of
@@ -4362,7 +4744,7 @@ version 2005/12/01 or later.
         { 
           \cs_if_free:cTF 
             { pgf@sh@ns@wa - \l_@@_prefix_str - \l_tmpa_int - v }
-            { \@@_error:n { Inexistent~v-node } }
+            { \@@_fatal:n { Inexistent~v-node } }
             { 
               \tikz@parse@node\pgfutil@firstofone ( \l_tmpa_int - v )
               \dim_set:Nn \l_tmpa_dim \pgf@x
@@ -4373,6 +4755,7 @@ version 2005/12/01 or later.
     \end { tikzpicture } 
 %    \end{macrocode}
 % 
+%
 % \bigskip
 % The code in |\@@_post_halign:| is common to |{WithArrows}| and
 % |{DispWithArrows}|.
@@ -4386,12 +4769,16 @@ version 2005/12/01 or later.
 %    \begin{macrocode}
     \bool_if:nT \c_@@_mathtools_loaded_bool
       { \MH_if_boolean:nT { show_only_refs } \MT_showonlyrefs_true: }
-    \bool_if:NTF \l_@@_inlabel_bool
+    \bool_if:NTF \l_@@_in_label_or_minipage_bool
       { 
-        $ % $
+        \c_math_toggle_token
         \skip_vertical:N \belowdisplayskip
       }
-      { $$ }
+      { \c_math_toggle_token \c_math_toggle_token }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+    \bool_if:NT \l_@@_subequations_bool { \end { subequations } }
 %    \end{macrocode}
 %
 % \bigskip 
@@ -4399,7 +4786,7 @@ version 2005/12/01 or later.
 % extract the footnotes with an environment |{savenotes}| (of the package
 % \pkg{footnote} or the package \pkg{footnotehyper}).
 %    \begin{macrocode}
-    \bool_if:NT \g_@@_footnote_bool { \end {savenotes } }
+    \bool_if:NT \g_@@_footnote_bool { \end { savenotes } }
     \ignorespacesafterend
   }
 %    \end{macrocode}
@@ -4435,7 +4822,7 @@ version 2005/12/01 or later.
     \bool_if:NTF \l_@@_in_WithArrows_bool
       { \@@_error:nn { Not~allowed~in~WithArrows } { #1 } }
       { 
-        \int_compare:nNnTF \g_@@_col_int < \l_@@_nb_of_columns_int
+        \int_compare:nNnTF \g_@@_col_int < \l_@@_nb_cols_int
           { \@@_error:nn { Not~allowed~in~DispWithArrows } { #1 } }
           { #2 }
       }
@@ -4443,18 +4830,25 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 % 
 % \bigskip
-% The command |\@@_notag:| will be linked to |\notag| and |\nonumber| in the
-% environments |{WithArrows}| and |{DispWithArrows}|.
+% The command |\@@_notag:| will be linked to the command |\notag| and also to
+% in the environments |{WithArrows}| and |{DispWithArrows}|. 
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_notag: 
   { \@@_if_in_last_col_of_disp:Nn \notag { \clist_clear:N \l_@@_tags_clist } }
 %    \end{macrocode}
 % 
-%
 % \bigskip
-% The command |\@@_tag| will be linked to |\tag| in the environments
-% |{WithArrows}| and |{DispWithArrows}|. We use |\NewDocumentCommand| because
-% this command has a starred version.
+% The command |\@@_nonumber:| will be linked to the command |\nonumber| and also to
+% in the environments |{WithArrows}| and |{DispWithArrows}|. 
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_nonumber: 
+  { \@@_if_in_last_col_of_disp:Nn \nonumber { \clist_clear:N \l_@@_tags_clist } }
+%    \end{macrocode}
+%
+% \bigskip 
+% The command |\@@_tag| will be linked to |\tag| in |{WithArrows}| and
+% |{DispWithArrows}|. We do the definition with |\NewDocumentCommand| because this
+% command has a starred version.
 %    \begin{macrocode}
 \NewDocumentCommand \@@_tag { s m } 
   { 
@@ -4524,8 +4918,8 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 % \bigskip
-% The command |\@@_tagnextline:| will be linked to |\tagnextline| in the
-% environments |{DispWithArrows}|.
+% The command |\@@_tagnextline:| will be linked to |\tagnextline| in 
+% |{DispWithArrows}|.
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_tagnextline:
   { 
@@ -4549,7 +4943,8 @@ version 2005/12/01 or later.
 \cs_new_protected:Npn \@@_set_qedhere: { \cs_set_eq:NN \qedhere \@@_qedhere: }  
 %    \end{macrocode}
 %
-% In the third column of the |\halign| of |{DispWithArrows}|, a command
+% In the last column of the |\halign| of |{DispWithArrows}| (column of the
+% labels, that is to say the numbers of the equations), a command
 % |\@@_qedhere_i:| will be issued if the flag |\l_@@_qedhere_bool| has been
 % raised. The code of this command is an adaptation of the code of |\qedhere| in
 % \pkg{amsthm}.
@@ -4686,7 +5081,7 @@ version 2005/12/01 or later.
         \int_compare:nNnTF \l_@@_final_int > \g_@@_line_int
           { 
             \int_compare:nNnF \l_@@_pos_arrow_int = 8
-              { \_@@_error:n { Too~few~lines~for~an~arrow } }
+              { \@@_error:n { Too~few~lines~for~an~arrow } }
           }
           \@@_code_for_possible_arrow:
 %    \end{macrocode}
@@ -4703,7 +5098,7 @@ version 2005/12/01 or later.
 % arrows. If we are in option |group| and in the first step of treatment
 % (|\l_@@_pos_arrow_int| = 7), we don't draw because, in the first step, we
 % don't draw anything. If there is no arrow in the group, we don't draw (this
-% situation occurs when all the arrows of the potential group arrives after the
+% situation occurs when all the arrows of the potential group arrive after the
 % last line of the environment).
 %    \begin{macrocode}
     \bool_if:nT
@@ -4721,9 +5116,10 @@ version 2005/12/01 or later.
 \cs_new_protected:Npn \@@_code_for_possible_arrow:
   { 
 %    \end{macrocode}
-% We test if the previous arrow was in fact the last arrow of a group. In this
-% case, we have to draw all the arrows of that group, except if we are with the
-% option |group| and in the first step of treatment (|\l_@@_pos_arrow_int| = 7).
+% We test whether the previous arrow was in fact the last arrow of a group. In
+% this case, we have to draw all the arrows of that group, except if we are with
+% the option |group| and in the first step of treatment (|\l_@@_pos_arrow_int| =
+% 7). 
 %    \begin{macrocode}
     \bool_if:nT 
       { 
@@ -4997,7 +5393,7 @@ version 2005/12/01 or later.
 % first line of the group and in |\l_@@_last_arrows_seq| the list of
 % all the arrows ending at the last line of the group. We compute these values
 % in the booleans |\l_tmpa_bool| and |\l_tmpb_bool|. These computations can't be
-% done in the following |{tikzpicture}| because the command |\seq_if_in:NTF|
+% done in the following |{tikzpicture}| because the command |\seq_if_in:NnTF|
 % which is \emph{not} expandable.
 %    \begin{macrocode}
     \seq_if_in:NxTF \l_@@_first_arrows_seq 
@@ -5144,11 +5540,11 @@ version 2005/12/01 or later.
     \tikz@parse@node \pgfutil@firstofone ( @@_label.west )
 %    \end{macrocode}
 % We compute in |\l_tmpa_dim| the maximal width possible for the label. 
-% |0.3333 em| is the default value of |inner sep| in the nodes of Tikz. Maybe we
-% should put the exact Tikz parameter. Here is the use of |\g_@@_right_x_dim|
-% which has been computed previously with the |v|-nodes.
+% Here is the use of |\g_@@_right_x_dim| which has been computed previously with
+% the |v|-nodes. 
 %    \begin{macrocode}
-    \dim_set:Nn \l_tmpa_dim { \g_@@_right_x_dim - \pgf@x - 0.3333 em } 
+    \dim_set:Nn \l_tmpa_dim 
+      { \g_@@_right_x_dim - \pgf@x - \pgfkeysvalueof { / pgf / inner~xsep } } 
 %    \end{macrocode}
 % We retrieve in |\g_tmpa_tl| the current value of the Tikz parameter 
 % ``|text width|''.\footnote{In fact, it's not the current value of 
@@ -5248,11 +5644,11 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 % \bigskip
-% A sequence of the options available in |\Arrow| in |\code-after|. This sequence
+% A sequence of the options available in |\Arrow| in |code-after|. This sequence
 % will be used in the error messages and can be modified dynamically.
 %    \begin{macrocode}
 \seq_new:N \l_@@_options_Arrow_code_after_seq
-\seq_set_from_clist:Nn \l_@@_options_Arrow_code_after_seq
+\@@_set_seq_of_str_from_clist:Nn \l_@@_options_Arrow_code_after_seq
   { ll, lr, rl, rr, tikz, tikz-code, v, x, offset }
 %    \end{macrocode}
 % 
@@ -5268,7 +5664,8 @@ version 2005/12/01 or later.
       \bool_set_false:N \l_@@_initial_r_bool
       \bool_set_false:N \l_@@_final_r_bool
       \int_case:nn \l_@@_pos_arrow_int
-        { 0
+        { 
+          0
             { 
               \bool_set_true:N \l_@@_initial_r_bool
               \bool_set_true:N \l_@@_final_r_bool
@@ -5445,9 +5842,64 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 %    \begin{macrocode}
+\@@_msg_new:nn { amsmath~not~loaded }
+  {
+    You~can't~use~the~option~'\l_keys_key_tl'~because~the~
+    package~'amsmath'~has~not~been~loaded.\\
+    If~you~go~on,~this~option~will~be~ignored~in~the~rest~
+    of~the~document.
+  }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\@@_msg_new:nn { Bad~value~for~replace~brace~by }
+  {
+    Bad~value~for~the~option~'\l_keys_key_tl'.~The~value~must~be~
+    an~extensible~left~delimiter.~The~possible~values~are:~
+    \token_to_str:N \{,~(,~[,~\token_to_str:N \lbrace,~
+    \token_to_str:N \lbrack,~\token_to_str:N \lgroup,~
+    \token_to_str:N \langle,~\token_to_str:N \lmoustache,~
+    \token_to_str:N \lfloor\ and~\token_to_str:N \lceil\ 
+    (and~\token_to_str:N \lvert\ and~\token_to_str:N \lVert\
+    if~amsmath~or~unicode-math~is~loaded).\\
+    \c_@@_option_ignored_str 
+  }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\@@_msg_new:nn { option~of~cr~negative }
+  {
+    The~argument~of~the~command~\token_to_str:N\\~
+    should~be~positive~in~the~row~\int_use:N \g_@@_line_int\
+    of~your~environment~\{\l_@@_type_env_str\}.\\
+    \c_@@_option_ignored_str
+  }
+%    \end{macrocode}
+% 
+%    \begin{macrocode}
+\@@_msg_new:nn { omit~probably~used } 
+  {
+    There~is~a~problem.~Maybe~you~have~used~a~command~
+    \token_to_str:N\omit\ in~the~line~\int_use:N \g_@@_line_int\
+    (or~another~line)~of~your~environment~\{\l_@@_type_env_str\}.\\ 
+    You~can~go~on~but~you~may~have~others~errors.
+  }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\@@_msg_new:nn { newline~at~the~end~of~env }
+  { 
+    Your~environment~\{\l_@@_type_env_str\}~should~not~end~with~
+    a~\token_to_str:N \\.\\
+    This~warning~might~become~an~error~in~a~future~version.
+  }
+%    \end{macrocode}    
+%
+%    \begin{macrocode}
 \@@_msg_new:nn { Invalid~option~format }
   {
-    The~option~'format'~should~contain~only~letters~r,~c~and~l.\\
+    The~key~'format'~should~contain~only~letters~r,~c~and~l~and~
+    must~not~be~empty.\\  
     \c_@@_option_ignored_str
   }
 %    \end{macrocode}
@@ -5463,10 +5915,10 @@ version 2005/12/01 or later.
 %    \begin{macrocode}          
 \@@_msg_new:nnn { Unknown~option~in~Arrow }
   { 
-    The~option~'\l_keys_key_tl'~
-    is~unknown~for~the~command~\l_@@_string_Arrow_for_msg_str\
-    in~the~row~\int_use:N \g_@@_line_int\
-    of~your~environment~\{\l_@@_type_env_str\}. \\
+    The~key~'\l_keys_key_tl'~is~unknown~for~the~command~
+    \l_@@_string_Arrow_for_msg_str\ in~the~row~
+    \int_use:N \g_@@_line_int\ of~your~environment~
+    \{\l_@@_type_env_str\}. \l_tmpa_str \\
     \c_@@_option_ignored_str \\
     For~a~list~of~the~available~keys,~type~H~<return>.
   }
@@ -5480,7 +5932,7 @@ version 2005/12/01 or later.
 %    \begin{macrocode}          
 \@@_msg_new:nnn { Unknown~option~WithArrows }
   {
-    The~option~'\l_keys_key_tl'~is~unknown~in~\{\l_@@_type_env_str\}. \\
+    The~key~'\l_keys_key_tl'~is~unknown~in~\{\l_@@_type_env_str\}. \\
     \c_@@_option_ignored_str \\
     For~a~list~of~the~available~keys,~type~H~<return>.
   }
@@ -5493,7 +5945,7 @@ version 2005/12/01 or later.
 %    \begin{macrocode}          
 \@@_msg_new:nnn { Unknown~option~DispWithArrows }
   { 
-    The~option~'\l_keys_key_tl'~is~unknown~in~\{\l_@@_type_env_str\}. \\
+    The~key~'\l_keys_key_tl'~is~unknown~in~\{\l_@@_type_env_str\}. \\
     \c_@@_option_ignored_str \\
     For~a~list~of~the~available~keys,~type~H~<return>.
   }
@@ -5506,7 +5958,7 @@ version 2005/12/01 or later.
 %    \begin{macrocode}          
 \@@_msg_new:nnn { Unknown~option~WithArrowsOptions }
   { 
-    The~option~'\l_keys_key_tl'~is~unknown~in~
+    The~key~'\l_keys_key_tl'~is~unknown~in~
     \token_to_str:N \WithArrowsOptions. \\
     \c_@@_option_ignored_str \\
     For~a~list~of~the~available~keys,~type~H~<return>. 
@@ -5520,9 +5972,8 @@ version 2005/12/01 or later.
 %    \begin{macrocode}
 \@@_msg_new:nnn { Unknown~option~Arrow~in~code-after }
   { 
-    The~option~'\l_keys_key_tl'~is~unknown~in~
-    \token_to_str:N \Arrow\
-    in~\token_to_str:N \code-after. \\
+    The~key~'\l_keys_key_tl'~is~unknown~in~
+    \token_to_str:N \Arrow\ in~code-after. \\
     \c_@@_option_ignored_str \\
     For~a~list~of~the~available~keys,~type~H~<return>.
   }
@@ -5537,7 +5988,7 @@ version 2005/12/01 or later.
 \@@_msg_new:nn { Too~much~columns~in~WithArrows }
   { 
     Your~environment~\{\l_@@_type_env_str\}~has~\int_use:N 
-    \l_@@_nb_of_columns_int\ columns~and~you~try~to~use~one~more.~
+    \l_@@_nb_cols_int\ columns~and~you~try~to~use~one~more.~
     Maybe~you~have~forgotten~a~\c_backslash_str\c_backslash_str.~
     If~you~really~want~to~use~more~columns~(after~the~arrows)~you~should~use~ 
     the~option~'more-columns'~at~a~global~level~or~for~an~environment. \\
@@ -5549,10 +6000,10 @@ version 2005/12/01 or later.
 \@@_msg_new:nn { Too~much~columns~in~DispWithArrows }
   { 
     Your~environment~\{\l_@@_type_env_str\}~has~\int_use:N 
-    \l_@@_nb_of_columns_int\ columns~and~you~try~to~use~one~more.~
+    \l_@@_nb_cols_int\ columns~and~you~try~to~use~one~more.~
     Maybe~you~have~forgotten~a~\c_backslash_str\c_backslash_str\ 
     at~the~end~of~row~\int_use:N \g_@@_line_int. \\
-    If~you~go~on,~you~may~have~other~errors.
+    This~error~is~fatal.
   }
 %    \end{macrocode}
 %
@@ -5583,7 +6034,8 @@ version 2005/12/01 or later.
 %    \begin{macrocode}          
 \@@_msg_new:nn          
   { Too~few~lines~for~an~arrow }
-  { Line~\l_@@_input_line_str\
+  { 
+    Line~\l_@@_input_line_str\
     :~an~arrow~specified~in~the~row~\int_use:N \l_@@_initial_int\
     of~your~environment~\{\l_@@_type_env_str\}~can't~be~drawn~
     because~it~arrives~after~the~last~row~of~the~environment. \\
@@ -5605,7 +6057,7 @@ version 2005/12/01 or later.
   { 
     The~environment~\{\l_@@_type_env_str\}~should~be~used~only~outside~math~
     mode~like~the~environment~\{align\}~of~amsmath. \\ 
-    If~you~go~on,~you~will~have~other~errors.
+    This~error~is~fatal.
   }
 %    \end{macrocode}
 %
@@ -5639,7 +6091,8 @@ version 2005/12/01 or later.
 \@@_msg_new:nn { Arrow~not~in~last~column }
   { 
     You~should~use~the~command~\l_@@_string_Arrow_for_msg_str\
-    only~in~the~last~column~of~your~environment~\{\l_@@_type_env_str\}.\\
+    only~in~the~last~column~(column~\int_use:N\l_@@_nb_cols_int)~
+    of~your~environment~\{\l_@@_type_env_str\}.\\
     However~you~can~go~on~for~this~time.
   }
 %    \end{macrocode}
@@ -5694,7 +6147,8 @@ version 2005/12/01 or later.
 \@@_msg_new:nn { Not~allowed~in~DispWithArrows }
   { 
     The~command~\token_to_str:N #1
-    is~allowed~only~in~the~last~columnm~of~\{\l_@@_type_env_str\}. \\
+    is~allowed~only~in~the~last~column~
+    (column~\int_use:N\l_@@_nb_cols_int)~of~\{\l_@@_type_env_str\}. \\ 
     \c_@@_option_ignored_str
   }
 %    \end{macrocode}
@@ -5746,9 +6200,9 @@ version 2005/12/01 or later.
   {
     There~is~a~problem.~Maybe~you~have~put~a~command~\token_to_str:N\cr\
     instead~of~a~command~\token_to_str:N\\~at~the~end~of~
-    the~row~\int_use:N \l_tmpa_int\
+    the~row~\l_tmpa_int\
     of~your~environment~\{\l_@@_type_env_str\}. \\
-    If~you~go~on,~you~may~have~an~incorrect~output.
+    This~error~is~fatal.
   }
 %    \end{macrocode}
 %
@@ -5765,6 +6219,22 @@ version 2005/12/01 or later.
   }
 %    \end{macrocode}
 %
+%    \begin{macrocode}
+\@@_msg_new:nnn { Duplicate~name }
+  { 
+    The~name~'\l_keys_value_tl'~is~already~used~and~you~shouldn't~use~
+    the~same~environment~name~twice.~You~can~go~on,~but,~
+    maybe,~you~will~have~incorrect~results. \\
+    For~a~list~of~the~names~already~used,~type~H~<return>. \\ 
+    If~you~don't~want~to~see~this~message~again,~use~the~option~
+    'allow-duplicate-names'. 
+  }
+  {
+    The~names~already~defined~in~this~document~are:~
+    \seq_use:Nnnn \g_@@_names_seq { ,~ } { ,~ } { ~and~ }.
+  }
+%    \end{macrocode}
+%
 % 
 %
 % \subsection{The command \textbackslash WithArrowsNewStyle}
@@ -5782,9 +6252,11 @@ version 2005/12/01 or later.
             #1 .code:n = 
              { \keys_set_known:nn { WithArrows / WithArrowsOptions } { #2 } }
           } 
-        \seq_put_right:Nn \l_@@_options_WithArrows_seq {#1}
-        \seq_put_right:Nn \l_@@_options_DispWithArrows_seq { #1 }
-        \seq_put_right:Nn \l_@@_options_WithArrowsOptions_seq { #1 }
+        \seq_put_right:Nx \l_@@_options_WithArrows_seq { \tl_to_str:n { #1 } }
+        \seq_put_right:Nx \l_@@_options_DispWithArrows_seq 
+          { \tl_to_str:n { #1 } }
+        \seq_put_right:Nx \l_@@_options_WithArrowsOptions_seq 
+          { \tl_to_str:N { #1 } }
 %    \end{macrocode}
 % We now set the options in a TeX group in order to detect if some keys in |#2|
 % are unknown. If a key is unknown, an error will be raised. However, the key
@@ -5793,7 +6265,7 @@ version 2005/12/01 or later.
         \group_begin:
           \msg_set:nnn { witharrows } { Unknown~option~WithArrowsOptions }
             {
-              The~option~'\l_keys_key_tl'~can't~be~set~in~the~
+              The~key~'\l_keys_key_tl'~can't~be~set~in~the~
               definition~of~a~style.~You~can~go~on~for~this~time~
               but~you~should~suppress~this~key. 
             }
@@ -5822,7 +6294,7 @@ version 2005/12/01 or later.
 % This code is the only part of the code of \pkg{witharrows} which uses the
 % package \pkg{varwidth} and also the Tikz library |calc|. That's why we have
 % decided not to load this package and this library. If they are not loaded, the
-% user will have an error only if he uses the option |up| or the option |down|.
+% user will have an error only when using the option |up| or the option |down|.
 % 
 % \medskip
 % The token list |\c_@@_tikz_code_up_tl| is the value of |tikz-code| which will
@@ -5919,6 +6391,8 @@ version 2005/12/01 or later.
         }
   }
 %    \end{macrocode}
+%
+%    
 % 
 %    \begin{macrocode}
 \seq_put_right:Nn \l_@@_options_Arrow_seq { down }
@@ -5944,24 +6418,8 @@ version 2005/12/01 or later.
     \c_@@_option_ignored_str
   }
 %    \end{macrocode}
-% 
-%    \begin{macrocode}
-\@@_msg_new:nnn { Duplicate~name }
-  { 
-    The~name~'\l_keys_value_tl'~is~already~used~and~you~shouldn't~use~
-    the~same~environment~name~twice.~You~can~go~on,~but,~
-    maybe,~you~will~have~incorrect~results. \\
-    For~a~list~of~the~names~already~used,~type~H~<return>. \\ 
-    If~you~don't~want~to~see~this~message~again,~use~the~option~
-    'allow-duplicate-names'. 
-  }
-  {
-    The~names~already~defined~in~this~document~are:~
-    \seq_use:Nnnn \g_@@_names_seq { ,~ } { ,~ } { ~and~ }.
-  }
-%    \end{macrocode}
-%
 %
+% 
 % \section{History}
 %
 % \subsection*{Changes between versions 1.0 and 1.1}
@@ -6081,7 +6539,7 @@ version 2005/12/01 or later.
 %
 % \smallskip
 % Replacement of some options |O { }| in commands and environments defined with
-% \pkg{xparse} by |! O { }| (because a recent version of \pkg{xparse} introduced
+% \pkg{xparse} by |! O { }| (a recent version of \pkg{xparse} introduced
 % the specifier |!| and modified the default behaviour of the last optional
 % arguments:
 % |//www.texdev.net/2018/04/21/xparse-optional-arguments-at-the-end|).
@@ -6123,7 +6581,21 @@ version 2005/12/01 or later.
 % \subsection*{Changes between 1.16 and 1.17}
 % 
 % Option |format|
+%
+% \subsection*{Changes between 1.17 and 1.18}
+%
+% New option |<...>| for |{DispWithArrows}|.
+%
+% Option |subequations|.
+%
+% Warning when |{WithArrows}| or |{DispWithArrows}| ends by "\\".
 % 
+% No space before an environnement |{DispWithArrows}| if we are at the beginning
+% of a |{minipage}|.
+% \PrintIndex
+%
+% \tableofcontents
+%
 % \endinput
 % Local Variables:
 % TeX-fold-mode: nil