From: Doug Ewell (dewell@adelphia.net)
Date: Wed Aug 18 2004 - 10:29:34 CDT
<Bob underscore Hallissy at sil dot org> wrote:
> As has been mentioned previously on this list (and I would like to see
> it added to http://www.unicode.org/faq/middleeast.html):
>
> This is not a reliable technique because not all Arabic characters
> have a complete set of presentation forms encoded in Unicode. Ernst
> Tremel mentioned on this list in February at least a few such:
>
> [list of missing small-v forms]
You are correct. This was just intended as a starting point for Nitin,
who was previously under the impression that the underlying character
had to change.
> Presentation forms are no longer being added to Unicode.
Thanks, I did know that. :-)
> Modern rendering systems use additional data in the font (e.g.,
> OpenType, Graphite, or AAT tables) to indicate which glyph to use for
> a given character in a given context, without dependence on
> presentation form glyphs being "encoded" (i.e., given Unicode
> codepoints)
If Nitin had a "modern rendering system" to work with, he wouldn't have
been asking these questions, because he already would have been getting
the correct behavior. Non-modern systems that display a series of
nominal glyphs when the user enters U+06xx characters are what cause
users to invent their own techniques.
-Doug Ewell
Fullerton, California
http://users.adelphia.net/~dewell/
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