[XeTeX] Charis SIL glyph variants

[Benct Philip Jonsson]

On 2008-11-17 Jonathan Kew wrote:
> %%%%%% test file %%%%%%%
> \font\x="Charis SIL" at 12pt
> \font\y="Charis SIL/GR:Uppercase Eng alternates=Large eng 
> on baseline"  
> at 12pt
> 
> \x This is Charis with the default capital Eng, J.
> 
> \y This is Charis with an alternate capital Eng, J.
> 
> \end
> %%%%%% end %%%%%%%

Thanks for the help.  I have some follow-up
questions, however.

So I can't get at it through fontspec?
Do I have to use TeX rather than LaTeX font definition
commands?  I have nothing against it, I just want to know.

Perhaps I could do something like

%%% example %%%

\font\alteng="Charis SIL/GR:Uppercase Eng alternates=Large 
eng on baseline" at 11pt
\[re]newcommand{\NG}{\alteng\char"014A}

% And then in the document

VƏ\NG HUŠ

%%% end %%%

> Although both capital Eng characters in the source are 
> simply U+014A,  
> they will render with different glyphs because of the 
> optional feature  
> applied in the second font definition.
> 
> **WARNING**
> 
> Unfortunately, it turns out that a bug in xetex 0.999.6 
> (and earlier)  
> means that it will go into an infinite loop if you try 
> this, but if  
> you can build 0.999.7 from the source in Subversion (from 
> either the  
> xetex or texlive repositories), it should work.

So I'll have to compile it myself? :-/

What are the right commands, including those to
download from Subversion?  Mind you I'm originally a
philologist, not a computer scientist, and I just
recently went over to Linux!


/BP 8^)>
-- 
Benct Philip Jonsson -- melroch atte melroch dotte se
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  "C'est en vain que nos Josués littéraires crient
  à la langue de s'arrêter; les langues ni le soleil
  ne s'arrêtent plus. Le jour où elles se *fixent*,
  c'est qu'elles meurent."           (Victor Hugo)