bug#20140: 24.4; M17n shaper output rejected

[Eli Zaretskii]

> Date: Mon, 14 Feb 2022 22:14:27 +0000
> From: Richard Wordingham <richard.wordingham@ntlworld.com>
> Cc: 20140@debbugs.gnu.org, larsi@gnus.org
> 
> > > You should also add CGJ and ZWNJ, and some people may appreciate
> > > ZWJ - the Khottabun font has ligatures involving ZWJ, though it may
> > > just be an experimental feature - and ultimately WJ, for when
> > > someone writes a Tai Tham word breaker.  
> > 
> > How should I add CGJ and ZWNJ?  What are the rules?
> > 
> > > Oh, and Thai and Lao mai t(r)i and mai chat(t)awa and U+0324
> > > COMBINING DIAERESIS BELOW turn up occasionally - U+0324 is supported
> > > in Thep's Khottabun font, and my Da Lekh series supports Thai mai
> > > tri and mai chattawa. These characters seem to work with HarfBuzz.  
> > 
> > Not sure I understand: what patterns/rules should be added for these?
> 
> Add them all to "M" in the definition of tai-tham-composable-pattern.
> Strictly, U+0324 should also be added to "S", but I'd be surprised to
> see it in a genuine spelling.

Thanks, done.