[latex3-commits] [latex3/latex3] gh1595: Extend docs on OpenType test (dcf0cc664)

[github at latex-project.org]

Repository : https://github.com/latex3/latex3
On branch  : gh1595
Link       : https://github.com/latex3/latex3/commit/dcf0cc664606cfae1cb306a4f7f489066be255fc

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

commit dcf0cc664606cfae1cb306a4f7f489066be255fc
Author: Joseph Wright <joseph at texdev.net>
Date:   Wed Nov 6 11:54:54 2024 +0000

    Extend docs on OpenType test


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

dcf0cc664606cfae1cb306a4f7f489066be255fc
 l3kernel/l3sys.dtx | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/l3kernel/l3sys.dtx b/l3kernel/l3sys.dtx
index af8f35439..583ef0220 100644
--- a/l3kernel/l3sys.dtx
+++ b/l3kernel/l3sys.dtx
@@ -114,7 +114,17 @@
 %   \end{syntax}
 %   Conditional which allows functionality-specific code to be used.
 %   The test is true for engines which can use OpenType fonts and
-%   thus full Unicode typesetting: currently \XeTeX{} and \LuaTeX{}.
+%   thus full Unicode typesetting. This tests for features not engine
+%   name, but currently is equivalent to requiring either
+%   \XeTeX{} or \LuaTeX{}.
+%   \begin{texnote}
+%     The underlying test here checks for \tn{Umathcode}, which
+%     is used to implement OpenType math font typesetting. Any
+%     engine which should give a \texttt{true} result here needs
+%     to provide general Unicode support (accepting the full UTF-8
+%     range for character codes), a mechanism to load system fonts
+%     and a suitable interface for math mode typesetting.
+%   \end{texnote}
 % \end{function}
 %
 % \begin{variable}[added = 2015-09-19]{\c_sys_engine_str}