Re: Joining Arabic Letters

From: Philippe Verdy <>
Date: Sun, 1 Apr 2012 20:22:12 +0200

Le 1 avril 2012 19:24, Christopher Fynn <> a écrit :
> Even then
> it would require some protocol  allowing the lookups in each font to
> interact.

There's smart mechanism indicated in this list, used by OpenOffice,
that uses ZWJ for this purpose.

I think it is a **great **suggestion that should be documented because
it is full part of the standard (ZWJ and ZWNJ **have** been assigned
standard joining types). It will work at least to correctly respect
the standardized joining types for **all** base letters (not just in
the Arabic script, but in other Semitic scripts that uses joining
types as well).

It will of course not work for supporting the correct positioning (or
ligation) of diacritics, for which a renderer may just be able to use
a default position, which may not work very well, but that will be
still correct according to the standard.

It will not work for diacritics that have not been encoded separately
in the Arabic script (such as 1/2/3/4 dots above or below, pointing
upwards or downwards, horizontally or vertically, and Persian-Urdu
digits above...), only to avoid the non-normalization issues with
letters that are not decomposable in the basic Arabic abjad (but still
logically decomposable in some *alphabets* or abjads using the Arabic

-- Philippe.
Received on Sun Apr 01 2012 - 13:26:32 CDT

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