[latex3-commits] [git/LaTeX3-latex3-latex3] main: make small changes to the documentation of align-safe groups (b1a28983c)

[Bruno Le Floch]

Repository : https://github.com/latex3/latex3
On branch  : main
Link       : https://github.com/latex3/latex3/commit/b1a28983ca5f150cf2d60e9e08b646424ad0eb4c

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

commit b1a28983ca5f150cf2d60e9e08b646424ad0eb4c
Author: Jonathan Spratte <jspratte at yahoo.de>
Date:   Sat May 8 22:22:54 2021 +0200

    make small changes to the documentation of align-safe groups


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

b1a28983ca5f150cf2d60e9e08b646424ad0eb4c
 l3kernel/l3prg.dtx | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/l3kernel/l3prg.dtx b/l3kernel/l3prg.dtx
index 70df08c7b..4c85c7e1b 100644
--- a/l3kernel/l3prg.dtx
+++ b/l3kernel/l3prg.dtx
@@ -1620,7 +1620,7 @@
 %   \TeX{}'s alignment structures present many problems. As Knuth says
 %   himself in \emph{\TeX : The Program}: \enquote{It's sort of a miracle
 %   whenever \tn{halign} or \tn{valign} work, [\ldots]} One problem relates
-%   to commands that internally issues a \tn{cr} but also peek ahead for
+%   to commands that internally issue a \tn{cr} but also peek ahead for
 %   the next character for use in, say, an optional argument. If the
 %   next token happens to be a |&| with category code~4 we get some
 %   sort of weird error message because the underlying
@@ -1631,8 +1631,12 @@
 %   special group so that \TeX{} still thinks it's on safe ground but at
 %   the same time we don't want to introduce any brace group that may
 %   find its way to the output. The following functions help with this
-%   by using code documented only in Appendix~D of
+%   by using behaviour documented only in Appendix~D of
 %   \emph{The \TeX{}book}\dots
+%   In short evaluating |`{| and |`}| as numbers will not change the counter
+%   \TeX{} uses to keep track of its state in an alignment, whereas gobbling a
+%   brace using \cs{if_false:} will affect \TeX's state without producing any
+%   real group.
 %   We place the \cs{if_false:} |{| \cs{fi:} part at that place so
 %   that the successive expansions of \cs{group_align_safe_begin/end:}
 %   are always brace balanced.