[latex3-commits] [git/LaTeX3-latex3-luaotfload] dev: Document upper changes (1f01c9a)

[Marcel Fabian Krüger]

Repository : https://github.com/latex3/luaotfload
On branch  : dev
Link       : https://github.com/latex3/luaotfload/commit/1f01c9a3407a4e17a25693e94ad4357cd3e291f3

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

commit 1f01c9a3407a4e17a25693e94ad4357cd3e291f3
Author: Marcel Fabian Krüger <tex at 2krueger.de>
Date:   Thu Apr 28 19:37:48 2022 +0200

    Document upper changes


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

1f01c9a3407a4e17a25693e94ad4357cd3e291f3
 doc/luaotfload-main.tex | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/doc/luaotfload-main.tex b/doc/luaotfload-main.tex
index d9798b8..6005aea 100644
--- a/doc/luaotfload-main.tex
+++ b/doc/luaotfload-main.tex
@@ -1355,16 +1355,30 @@ obviously, \inlinecode{random}.
   \beginaltitem {upper/lower}
    The\phantomsection\label{upperlower}\marginpar{New in 3.16}
    font features \texttt{upper} and \texttt{lower} can be used to map
-   the text of a font to upper or lowercase before displaying it. Currently
-   this implements the untailored Unicode case mapping algorithm, but it is
-   planned to add tailoring later. For example
+   the text of a font to upper or lowercase before displaying it.
+
+   By default the casemapping is automatically tailored based on the active
+   \texttt{language} font feature. This automatic tailoring can be overwritten
+   by passing a two letter language tag to the \texttt{upper} or \texttt{lower}
+   feature. In addition to ordinary language tags, the tags \texttt{el-xiota}
+   and \texttt{de-xeszett} can be used. \texttt{el-xiota} adapts the greek
+   rules for uppercasing to keep iota subscripts as combining characters which
+   sufficiently well behaving fonts can render in appropriate ways while the
+   default for greek is to convert these into capital iotas. \texttt{de-xeszett}
+   adapts uppercasing for german to use the capital eszett instead of
+   uppercasing the eszett to double capital s.
 
    \beginlisting
-   \font\test={name:LatinModernRoman:mode=node;+upper;}
+   \font\test={kpse:LinLibertine_R.otf:mode=node;+upper;}
+   \test Grüße
+   \font\test={kpse:LinLibertine_R.otf:mode=node;upper=de-xeszett;}
    \test Grüße
    \endlisting
 
-   {\Large\font\test={name:LatinModernRoman:mode=node;+upper;}\test Grüße}
+   {\Large
+     \font\test={kpse:LinLibertine\string_R.otf:mode=node;+upper;}\test Grüße
+     \font\test={kpse:LinLibertine\string_R.otf:mode=node;upper=de-xeszett;}\test Grüße
+   }
 
   \endaltitem