Re: letters that "complete the rectangle" in Indic scripts

From: Philippe Verdy <>
Date: Thu, 19 Sep 2013 10:42:43 +0200

2013/9/19 Richard Wordingham <>

> On Wed, 18 Sep 2013 04:38:05 +0200
> Philippe Verdy <> wrote:
> > Don't know what you mean here really, but the Indic scripts work at a
> > core syllabic C-V level, and in order to fit with real languages, it
> > was effectively necessary to fill the holes by inventing the implicit
> > concept of null consonnants that combine with vowels, even of these
> > compound are not breakable in the common sense (so we have now
> > combining vowels, and plain vowel "letters").
> As far as I am aware, a proper 'null consonant' has only arisen when
> it actually represents a glottal stop.
> > ... vowels
> > are gven second degree of importance (true for all Semitic abjads and
> > Indic abugidas).
> I'm not sure that that is true. In Thai, vowel marks placed before or
> after the consonant are classified as letters in Unicode, and that is a
> fair reflection of how they are treated in uncomputerised contexts.
> Moreover, when writing is not cramped vertically, most of the vowels
> above can be as big as the consonants. (Many Thai fonts constrain the
> ink of one line to be below the ink of the previous line, and that
> causes cramping.)

True, but the Thai script is definitely not encoded in the UCS with the
logical Indic model, but has kept the logic of the prior legacy TIS
encoding (in reading order, not logicial order). So even if historically it
is an indic script, it behaves very differently from other Indic scripts
(which were based instead on the prior legacy ISCII encodings, themselves
derived from typewriter practices, later adapted by IBM working with the
Thai government).

So **within the UCS**, the Thai script is not an Indic script. There was so
many existing documents encoded like in TIS sctandards that preserving the
roundtrop compatibility was judged more essential than adopting the
logical Indic order for this script. This has consequences for some
algorithms, notably for collation.
Received on Thu Sep 19 2013 - 03:45:18 CDT

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