From b2ba0afced5c10391750914c16a2aa06cfaa6a96 Mon Sep 17 00:00:00 2001
From: Karl Berry <karl@freefriends.org>
Date: Sun, 22 Jan 2017 23:37:33 +0000
Subject: latex2e (22jan17)

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+% \iffalse meta-comment
+%
+% Copyright 2016
+% The LaTeX3 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
+%    http://www.latex-project.org/lppl.txt
+% and version 1.3c or later is part of all distributions of LaTeX
+% version 2005/12/01 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
+% Filename: ltnews26.tex
+%
+% This is issue 26 of LaTeX News.
+
+\documentclass{ltnews}
+\usepackage[T1]{fontenc}
+
+\usepackage{lmodern,url,hologo}
+
+\publicationmonth{January}
+\publicationyear{2017}
+
+\publicationissue{26}
+
+\begin{document}
+
+\maketitle
+\tableofcontents
+
+\setlength\rightskip{0pt plus 3em}
+\section{\eTeX{}}
+
+In \LaTeX{} News~16 (December 2003) the team announced
+\begin{quotation}
+We expect that within the next two years, releases of \LaTeX{} will
+change modestly in order to run best under an extended \TeX{} engine
+that contains the \eTeX{} primitives, e.g., \eTeX{} or pdf\TeX{}.
+\end{quotation}
+and also said
+\begin{quotation}
+Although the current release does not \emph{require} \eTeX{} features, we
+certainly recommend using an extended \TeX{}, especially if you need to debug
+macros.
+\end{quotation}
+
+For many years the team have worked on the basis that users will have \eTeX{}
+available but had not revisited the above statements formally. As of the
+January 2017 release of \LaTeXe{}, \eTeX{} is \emph{required} to build the
+format, and attempting to build a format without the extensions will fail.
+
+Practically, modern \TeX{} distributions provide the extensions in all engines
+other than the ``pure'' Knuth \texttt{tex}, and indeed parts of the
+format-building process already require \eTeX{}, most notably some of the UTF-8
+hyphenation patterns. As such, there should be no noticeable effect on users of
+this change.
+
+The team expect to make wider use of \eTeX{} within the kernel in future;
+details will be announced where they impact on end users in a visible way.
+
+\section{Default Encodings in \hologo{XeLaTeX} and \hologo{LuaLaTeX}}
+The default encoding in \LaTeX\ has always been the original
+128-character encoding \texttt{OT1}.  For Unicode based \TeX\ engines, this
+is not really suitable, and is especially problematic with
+\hologo{XeLaTeX} as in the major distributions this is built with
+Unicode based hyphenation patterns in the format.  In practice this has
+not been a major problem as documents use the contributed
+\textsf{fontspec} package in order to switch to a
+Unicode encoded font.
+
+In this release we are adding \texttt{TU} as a new supported
+encoding in addition to the previously supported encodings such as \texttt{OT1}
+and \texttt{T1}. This denotes a Unicode based font encoding. It is essentially
+the same as the \texttt{TU} encoding that has been on trial with the
+experimental \texttt{tuenc} option to \textsf{fontspec} for the past
+year.
+
+The \hologo{XeLaTeX} and \hologo{LuaLaTeX} formats will now default
+to \texttt{TU} encoding and \texttt{lmr} (Latin Modern) family. In the
+case of \hologo{LuaLaTeX} the contributed \textsf{luaotfload} Lua
+module will be loaded at the start of each run to enable the loading
+of OpenType fonts.
+
+The \textsf{fontspec} package is being adjusted in a companion release
+to recognise the new encoding default arrangements.
+
+Note that in practice no font supports the full Unicode range, and so
+\texttt{TU} encoded fonts, unlike fonts specified for \texttt{T1}, may be
+expected to be incomplete in various ways. In the current release the file
+\texttt{tuenc.def} that implements the \texttt{TU} encoding-specific commands
+has made some basic assumptions for (for example) default handling of
+accent commands, and the set of command names is derived from the
+command names used for the UTF-8 support in the \textsf{inputenc} package,
+restricted roughly to the character ranges classically provided by
+the \texttt{T1} and \texttt{TS1} encodings, but is part of a longer term plan
+seen over recent releases to increase support for Unicode based \TeX\ engines
+into the core \LaTeX\ support.
+
+
+
+If for any reason you need to process a document with the previous
+default \texttt{OT1} encoding, you may switch encoding in the usual ways, for
+example
+\begin{verbatim}
+\usepackage[OT1]{fontenc}
+\end{verbatim}
+or you may roll back all the changes for this release by starting the
+document with
+\begin{verbatim}
+\RequirePackage[2016/12/31]{latexrelease}
+\end{verbatim}
+
+\section{\cs{showhyphens} in \hologo{XeLaTeX}}
+Due to the way \hologo{XeLaTeX} interfaces to font libraries, the
+standard definition of \cs{showhyphens} does not work.  A variant
+definition has been available in the contributed \textsf{xltxtra}
+package, however a (slightly different) definition for \cs{showhyphens}
+is now included in \hologo{XeLaTeX} by default. As usual
+this change will be undone if an earlier
+release is specified using the \textsf{latexrelease} package.
+
+\section{The \textsf{fixltx2e} Package}
+As described in \LaTeX{} News~22, the \textsf{fixltx2e} package has become
+obsolete with the new update policy. Since 2015 it has just made a
+warning and exited.  In this release we have re-introduced all
+the code from the original fixes in the 2014 \LaTeX\ but guarded by
+\verb|\IncludeInRelease{2015/01/01}|.
+So for current releases \textsf{fixltx2e} still just makes a warning
+but for old releases, whether that is an old format, or a format with
+the version date reset via  the \textsf{latexrelease} package, the
+fixes in the original \textsf{fixltx2e} will be applied.
+
+This improves the ability to run old documents in a way compatible
+with contemporary formats. If you have a 2014 document that used
+\verb|\usepackage{fixltx2e}| and you add
+\verb|\RequirePackage[2014/01/01]{latexrelease}| and process it with the
+current format then \textsf{latexrelease} will undo most changes made
+since 2014, but now when the document includes \textsf{fixltx2e} it
+will act like a 2014 version of the package and apply the code fixes,
+not just give a warning that the package is obsolete.
+
+\section{The \textsf{latexbug} package}
+
+As explained in more detail
+at the \LaTeX\ Project
+  website\footnote{\url{https://www.latex-project.org/bugs/}}
+a new package, \textsf{latexbug}, has been produced to help produce
+test files to accompany bug reports on the core \LaTeX\ distribution.
+This is being published separately to CTAN at the same time as this
+release. By using the \textsf{latexbug} package you can easily check
+that the packages involved in the test are all part of the core
+release. The \LaTeX\ project can not handle bug reports on contributed
+packages, which should be directed to the package maintainer as given
+in the package documentation.
+
+\section{Updates to \textsf{amsmath}}
+The \textsf{amsmath} package has two updates at this release.
+\begin{itemize}
+\item The spacing to the left of the \texttt{aligned} and
+  \texttt{gathered} environments has been fixed: the spurious thin
+  space is no longer added by default. Package options control this
+  to revert to the original behaviour where required; see the
+  \textsf{amsldoc} guide for further details. 
+\item The large delimiters around generalised fractions (for example
+  in the \cs{binom} construct) did not work in previous releases if
+  using \hologo{LuaTeX} or \hologo{XeTeX} with OpenType math fonts. This is
+  related to the lack of specific metrics for this use in the OpenType Math
+  table. In principle \hologo{LuaTeX} has two additional named metrics
+  to control the delimiters but these are not initialised by default,
+  and in \hologo{XeTeX} it does not seem possible to make them work at all.
+  So for Unicode \TeX\ systems, a new implementation of
+  \cs{genfrac} is used at this release that uses \verb|\left\right|
+  internally but parameterised to give spacing as close to the
+  original as possible. The implementation in (pdf)\TeX\ is
+  unaffected.
+\end{itemize}
+
+\section{Updates to \textsf{tools}}
+The \textsf{array} package has been updated to fix a longstanding but
+previously unreported issue with unwanted interactions between tables
+in the page head or foot and the body of the page, as reported in
+\href{http://www.latex-project.org/cgi-bin/ltxbugs2html?pr=tools/4488}{PR
+  tools/4488}.
+There is also an update to the \hologo{LuaTeX} support in \textsf{bm}.
+
+\section{An addendum to the release changes in 2015}
+
+In 2015 we announced the introduction of the roll-back\slash
+roll-forward concept to manage bug fixes and additions to core
+\LaTeX{} in a manageable way. We also announced at that time
+that we now incorporate all fixes from \textsf{fixltx2e} into the
+kernel (as the old mechanism produced problems instead of improving
+the situation). Refer to
+\href{https://www.latex-project.org/news/latex2e-news/ltnews22.pdf}{\texttt{ltnews22.pdf}}
+for details.
+
+One of the fixes from \textsf{fixltx2e} was for a glaring bug in
+\cs{addvspace} that was originally detected in the mid-nineties and
+back then added to the \textsf{fixltx2e} support package. In certain
+situations \cs{addvspace} would result in a page/column break below
+the baseline of the last line. As a result documents using
+\cs{flushbottom} would show a clear misalignment (even more prominent
+when typesetting in two-column mode).
+
+Starting with release 2015/01/01 this is now finally corrected already
+in the kernel and not only in \textsf{fixltx2e}.  In nearly all
+circumstances this will either make no difference to existing
+documents, or it will locally improve the visual appearence of that
+document without changing anything on other pages.  However, by the
+nature of the change it is also possible that there are further
+non-local changes to the page breaks due to the different break
+positions introduced by the fix.
+
+Thus, for documents that have been written before 2015 and that should
+be preserved unchanged at all costs you may have to add
+\begin{verbatim}
+\RequirePackage[2014/01/01]{latexrelease}
+\end{verbatim}
+at the top of the document, to roll back the format to a date before
+the policy change.
+
+\end{document}
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