Re: Arabic lam-alef ligature in vocalized texts

From: John Hudson (tiro@tiro.com)
Date: Wed Nov 27 2002 - 10:29:30 EST

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    At 12:34 AM 11/27/2002, Amélie DELTOUR wrote:

    >How should the LAM-ALEF ligature be vocalized in Arabic according to Unicode?
    >In texts on the Internet, I find the codes in the following order for
    >instance: "U+0644 U+0627 U+064E" (LAM-ALEF-FATHA). The logical order would
    >rather be LAM-FATHA-ALEF.
    >The problem is that if the LAM-FATHA-ALEF order is used, then the LAM-ALEF
    >ligature is not recognized in common display programs (IE, NS6 or MS Word).

    It will be if the font is a correctly made OpenType font, and the software
    is using an appropriate version of Microsoft's Unicode Script Processor
    (Uniscribe), i.e. Windows 2000 or later. It is possible to make the
    ligature substitution lookups in the OpenType font ignore 'marks' such as
    FATHA. So the sequence LAM+FATHA+ALEF renders as LAM_ALEF+FATHA. OpenType
    glyph positioning than then be used to correctly place the FATHA over the
    LAM_ALEF ligature.

    >If I understand the Unicode Standard well, the FATHA should be treated as
    >a "transparent character" and should not disturb the representation of the
    >LAM-ALEF ligature. In that case, it would only be an implementation
    >problem of the display programs...

    Correct.

    >However, I can notice that on the Internet, in vocalized texts (Quran,
    >Bible) the LAM-ALEF ligature is most often bad vocalized : the diacritic
    >mark is before the ligature, or after, or in most cases is not there at
    >all (in particular in the case of "li + alef-hamza") - which is quite annoying.

    This is an incorrect implementation, probably resulting from a convention
    developed for an older font format in which this character ordering hack
    has been used to position the diacritic over the LAM_ALEF ligature.

    John Hudson

    Tiro Typeworks www.tiro.com
    Vancouver, BC tiro@tiro.com

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