[latex3-commits] [git/LaTeX3-latex3-latex2e] localalpha: document #676 in ltnews (14d35437)

[Frank Mittelbach]

Repository : https://github.com/latex3/latex2e
On branch  : localalpha
Link       : https://github.com/latex3/latex2e/commit/14d354372447ee119e32bb4ad25e7415d543d122

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

commit 14d354372447ee119e32bb4ad25e7415d543d122
Author: Frank Mittelbach <frank.mittelbach at latex-project.org>
Date:   Mon Sep 27 23:50:09 2021 +0200

    document #676 in ltnews


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

14d354372447ee119e32bb4ad25e7415d543d122
 base/doc/ltnews34.tex | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/base/doc/ltnews34.tex b/base/doc/ltnews34.tex
index aa7a9389..57e101e8 100644
--- a/base/doc/ltnews34.tex
+++ b/base/doc/ltnews34.tex
@@ -357,9 +357,10 @@ Similar commands exist for classes and there we have added the missing
 
 New implementation for \cs{counterwithout} and \cs{counterwithin} with
 an additional optional arg so it becomes a drop-in replacement for
-amsmath \cs{numberwithin}.
+amsmath \cs{numberwithin}. In the optional argument you can specify a
+counter formatting command, such as \cs{roman}, if absent it
+defaults to \cs{arabic}.
 
-\emph{write appropriate description}
 
 
 
@@ -451,9 +452,30 @@ can be easily shown in the terminal without \cs{csname} gymnastics.
 
 \subsection{Undo some math alphabet allocations if necessary}
 
-\emph{write}
-%
-\githubissue{000}
+\TeX{} or more exactly the 8-bit versions of \TeX, such as \pdfTeX{}
+have a hard limit of 16 in the number of different math font groups
+(\cs{fam}) that can be used in a single formula. For each symbol font
+declared (by a package or in the preamble) one math group is allocated
+and the same happens for each math alphabet, such as \cs{mathbf}, that
+has be used at least once somewhere in the document. Up to now math
+alphabet allocations were permanent, even if they were used only once
+and then never again with the result that in complex documents you
+could run out of available math font groups. The only remedy then was to
+define your own math version which is complicated and cumbersome.
+
+This has now been changed and a new counter
+\texttt{localmathalphabets} was introduced. It defines how many of the
+remaining slots are assigned only locally if new math alphabets need a
+math group.  Once the formula is finished the allocation or
+allocations are then undone, giving you a fighting chance to use
+different math alphabets in the next formula. The default value is 2
+but if you need more local alphabets because of the complexity of your
+document, you can set it to a higher value, e.g., 4 or 5. Setting it
+even higher is possible, but seldom useful, because many slots will be
+taken up by symbol fonts and those are always permanently allocated,
+whether used or not.
+%
+\githubissue{676}