From: Philippe Verdy (verdy_p@wanadoo.fr)
Date: Thu Mar 16 2006 - 08:53:42 CST
From: "Vinod Kumar" <rigvinod@gmail.com>
> TUS4 shows sample half forms for Devanagari (Table 9-1). Similar
> Sample subscript forms for Kannada, Oriya etc would help to widen the
> standard to other Indian scripts. Currently, Devanagari garners most
> of the attention and treatment and other scripts get an introduction
> that is "abbreviated but highlight any differences from Devanagari
> where appropriate"!
> The treatment of ZWJ/ZWNJ for the other scripts has been brought out
> and solved by Peter Constable.
>
> All the Indic scripts should have tables for 1) Sample half or
> subscript forms, 2) Sample conjuncts 3) conjuncts of consonant and
> signs.
I fully agree there. The missing conjuncts and subscripts forms, as well as the list of forms with special treatment like RA or RA+HALLANT logically coded before the consonnant cluster on which such sequences are treated like graphical diacritics is missing. This causeslots of confusion and errors in many fonts (as well asinteroperability problems, when documents are created with these fonts, notably for the web).
The problem is notable even with core fonts provided with Windows, or rendered with Uniscribe or in Internet Explorer, even when the fonts are correct (the most significant error is the case of the vowel sign I which is not displayed before the base letter in Bengali or Oriya or Gurmukhi).
I have now identified your combining glyphs: they are RA+HALLANT coded before a consonnant, and RA coded after a consonnant with hallant, for consonnants that have no half-form.
The TUS chapter 9 needs much revision, because it is soooo much incomplete... This could be done almost extensively for all these scripts,except possibly for Tibetanwhichhas very complex conjunct rules that may not be completely known exactly.
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