Re: Tibetan/Burmese/Khmer

From: John Clews (
Date: Wed Jan 15 1997 - 18:23:23 EST

In message <9701151903.AA00319@Unicode.ORG> Michael Forgey
wrote via unicode@Unicode.ORG:

> I am wondering why it was decided to include in Unicode 2.0, two
> encodings for each Tibetan consonant (one the nominal form, and the other
> the subjoined form). The syllabic principles of the Tibetan script seems
> to be about the same as for the Indian scripts; why not require encoding
> Tibetan dead consonants with the virama, as is required for Devanagari,
> etc?

I'm glad somebody asked that question! The only Tibetan system I have seen
acts like other ISCII and Unicode Indic systems in using he "base"
character codes for coding, and letting the implementation provide other

There has been very active discusion on the list regarding whether Unicode's
Indic characters needing just "base" characters or also "Glyph components"
too, with opinion coming down strongly on Unicode's and ISO/IEC 10646's
actual choice of using _just_ "base" characters, and letting the
implementation provide other glyphs. This avoids alternative spellings
which could cause prioblems in searching, indexing, comparisons, etc.

I applaud this dicesion and am 100% behind it.

However, I would be grateful for information on the following:
 - how does UCS Tibetan avoid the alternative spellings problem outlined
 - would a UCS Tibetan imlementation be "wrong" if it allowed just base
   characters to be input?

I would be extremely interested in answers to these two questions as well
as to the others repreduced below from Michael Forgey.

> Are the Tibetan subjoined characters considered to be equal to the
> nominal form preceded by VIRAMA; i.e., 0F90 = 0F84 + 0F40? If so, does
> one have the discretion to choose the method of encoding, and is either
> method preferred?
> Since distinct codes have been allocated for Tibetan subjoined
> consonants, is it expected that distinct codes will be allocated for
> Burmese and/or Khmer sub-consonants?

I look forward to replies, on or off the list.

                                   Yours sincerely

                                     John Clews

  John Clews (Chairman of ISO/TC46/SC2: Conversion of Written Languages)

SESAME Computer Projects, 8 Avenue Rd. * email: Harrogate, HG2 7PG, United Kingdom * telephone: +44 (0) 1423 888 432

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