Re: Arabic Implementation

From: Doug Ewell (
Date: Wed Aug 18 2004 - 10:29:34 CDT

  • Next message: Chris Jacobs: "Re: Arabic Implementation"

    <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
    > 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

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