From: Christopher Fynn (cfynn@gmx.net)
Date: Fri Aug 19 2005 - 01:25:14 CDT
Patrick Andries wrote:
> Does the GB 10840 Certfication require that Chinese Minority scripts be
> displayed properly (i.e Mongolian or Tibetan) ?
>
> Would greatly appreciate any details,
>
> P. A.
There are different levels of compliance ...
e.g. for displaying Tibetan at the lowest level of compliance you just
have to be able to display a defalt glyph for each character (e.g. a
glyph like those in
the io10646 / Unicode code charts) - without necessarily forming proper
ligatures (shaping). Of course this is pretty well useless for normal
users since, unless you display proper "stack" ligatures for conjuncts,
Tibetan text is pretty well unreadable.
For a higher level of compliance you will now have to be able to
properly display ligatures for a sub-set of about 1500 Tibetan
combinations ("Set A" used in modern publications)
For the highest (A+) level of compliance you will have to be able to
properly display proper ligatures for an additional set of over 5,500
Tibetan combinations ( ("Tibetan Set B" additional combinations found in
tradtional Tibetan texts).
This is further complicated since in some Chinese encodings and systems
they seem to use the combintatons (ligature gyphs) in their Tibetan sets
A and B as (pre-composed composite) *characters* mapped to fixed
Unicode PUA and supplementary PUA code points. While this avoids the
need for OpenType or similar shaping to properly dsplay Tibetan text it
means that text needs to be converted to (de-composed) Unicode for other
systems.
- Chris
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