Re: Level 1 and Level 2

From: Martin J Duerst (
Date: Fri Aug 30 1996 - 09:05:36 EDT

Michael Everson wrote:

>I've never been convinced that Level 1 and Level 2 of 10646 differ in any
>significant way. The "combining characters" which are actually Devanagari
>vowels, for instance, are only combining in the sense that their glyphs
>behave in a particular way as regards to the preceding character. There has
>been some discussion in WG2 regarding this, and I think in WG3 regarding
>the situation of Thai (level 2) and of Vietnamese (level 3) in 8859.

Sorry to disagree. From a user's point, the difference matters very
much, in particular for Indic scripts.
From an implementor's point, the Devanagari vowels combine
with the previous CLUSTER or consonants. According to ISCII
13194 :1991, the worst case is four consonants, to which you
have to add three viramas to connect them. Quite a lot more
lookahead (in this case for rendering) than for most accented
combinations :-).

Regards, Martin.

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