[latex3-commits] [git/LaTeX3-latex3-latex2e] develop: draft documentation for #982 in ltnews (b84d7319)

[Frank Mittelbach]

Repository : https://github.com/latex3/latex2e
On branch  : develop
Link       : https://github.com/latex3/latex2e/commit/b84d7319178987c4fa91a03e3325ff752b3242be

>---------------------------------------------------------------

commit b84d7319178987c4fa91a03e3325ff752b3242be
Author: Frank Mittelbach <frank.mittelbach at latex-project.org>
Date:   Sat Jan 21 23:28:38 2023 +0100

    draft documentation for #982 in ltnews


>---------------------------------------------------------------

b84d7319178987c4fa91a03e3325ff752b3242be
 base/doc/ltnews37.tex | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/base/doc/ltnews37.tex b/base/doc/ltnews37.tex
index 3fb6847d..11090545 100644
--- a/base/doc/ltnews37.tex
+++ b/base/doc/ltnews37.tex
@@ -145,6 +145,48 @@
 \section{Introduction}
 
 
+\section{Documentation improvements}
+
+
+\subsection{Displaying the exact release dates for \LaTeX{}}
+
+In some situations it is necessary to find out the exact release dates
+for older version of the \LaTeX{} format, for example, when you need
+to use different code in a package depending on the availablilty of a
+certain feature and you therefore want to use
+\cs{IfFormatAtLeastTF}\texttt\{\meta{date}\texttt\} or the
+rather horrible construction \verb/\@ifl at t@r\fmtversion{/\meta{date}\texttt\},
+if you
+want to cater for formats that are older than 2020.
+
+Or you know that your package is definitely not going to work with a
+format before a certain \meta{date}, in which case you could use
+\verb/\NeedsTeXFormat{LaTeX2e}[/\meta{date}\texttt] to ensure that any
+  user is alerted if their format is too old.
+
+The big problem is to know the exact \meta{date} to put into such
+commands and in the past that was not that easy to find. You could have 
+looked in the the file \file{changes.txt}, but that is hidden somewhere
+in your installation and if you try
+\verb*/texdoc -l changes.txt/ you get more than thirty results and the
+right file is by no means the first.
+
+\textsf{@muzimuzhi} kindly provided a patch for this, so that we now have
+the exact dates for each \LaTeX{} format listed in an easy to remember
+place: in \file{ltnews.pdf} and that file conveniently also contains all major
+features and changes to \LaTeX{} over the years\Dash one of which is
+most likely the reason you need the \meta{date} date in the first
+place.
+
+It is given in parentheses in the newsletter titles, thus
+ now you can easily find out that the \LaTeX3 programming layer was
+added on 2020-02-02 (because the date was so nice) and not on the
+first of the month.
+%
+\githubissue{982}
+
+
+
 \section{New or improved commands}