OTL, Lao and Uniscribe (was: Representative glyphs for combining kannada signs)

From: Richard Wordingham (richard.wordingham@ntlworld.com)
Date: Tue Mar 21 2006 - 20:20:46 CST

  • Next message: Mark Davis: "Re: FW: Representative glyphs for combining kannada signs"

    James Kass wrote:

    >> Does Lao genuinely need OTL? I can see how it can
    >> benefit from it, but that is not the same statement.

    > Dr. John M. Durdin has shown that Lao does not genuinely need OTL
    > in order to display legibly. If the combining marks which sometimes
    > can stack higher over other combining marks are in the font at the
    > higher positions as default, then the rendering is reasonable.

    Indeed. My question was largely rhetorical, based on my experience with
    Thai and an evaluation of the benefit of decomposing sara am.

    However, I'd forgotten that the Lao *script* actually does need OTL, though
    I still believe OTL is not needed to write the Lao language in Lao script.
    The problem arises when you have multiple tone marks, as in the Tai Dam
    examples at
    The problem there is that Lao consonants are used with Lao sound values
    rather than the etymologically equivalent Tai Dam values, and Laotian Tai
    Dam creates low consonants (based on 5-tone Vientiane pronunication?) using
    mai catawa (U+0ECB) rather like the new, circumflexed consonants in New Tai
    Lue. I presume it has had to create new consonants because the indubitably
    aspirated low consonants (derived from Indic voiced aspirates) have been
    discarded by Lao. (Northern Thai uses Central Thai phonation values rather
    than etymologically corresponding values, so retaining the consonants in Lao
    might not have made any difference.)

    The Tai Dam examples are ill-formed according to the current published
    Microsoft rules, but I would not be at all surprised if they were allowed in


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