RE: Query for Validity of Thai Sequence

From: Philippe Verdy (
Date: Thu Feb 15 2007 - 16:28:19 CST

  • Next message: Richard Wordingham: "Re: Query for Validity of Thai Sequence"

    Regarding the question of the validity of Thai sequences, the following
    specification of the Thai support in OpenType (here the HTML version
    available on Microsoft Typography website) is worth noting:


    Note that this small document reveals some effective requirements for the
    effective encoding of documents.


    This is important because it reveals what is supported and has chances to
    work on all major platforms (including Windows, MacOSX, Solaris and Linux).


    If there are cases not correctly handled in OpenType standard features for
    Thai, then there are chances that alternative solutions (based on alternate
    rendering engines) will not work in practice.

    So discussing this here without involving the OpenType support will have no
    effect, even if Thai is correctly handled at the Unicode string processing



    De : [] De la
    part de Lokesh Joshi
    Envoyé : jeudi 15 février 2007 20:24
    À :
    Cc : Peter Constable; John Hudson; Eric Muller; Richard Wordingham;
    Objet : Re: Query for Validity of Thai Sequence


     this is what i wanted to ask and verify earlier also:

    #5589: Thai layout broken for <0E25, 0E37, 0E4C>?

     Reporter: markus | Owner: eric
         Type: defect | Status: new
     Priority: major | Milestone: UNSCH
     Component: layout | Version:
    Resolution: | Keywords:
         Xref: | Java:
           Os: | Project: ICU4C
        Weeks: | Revw:

    Comment (by eric):

     According to <>
     key.htm and <>
    , the ICU implementation is correct. They say that U+0E37 has
     class AV3 and that U+0E4C has class AD1, and that AV1 does not compose
     with AV3.

    I think this makes sense, i also coded according to the char-class.pdf.

    On 2/11/07, <> wrote:

    My apologies
    below for" Quite the reverse is true" -- read "Quite the reverse is also


    > Yes, inpratice one canuse the script of any language to write another
    > language it is just a question of how big an adaption. Quite the
    > reverse is true a writing system is designed not to use certain
    > letters/ideogrammes so as to be different but at the same time is
    > related in some way. Having one's own writing system is often seen as
    > a matter of pride for many nations/ethnic-groups. I can think of few
    > cases where the primary reason for choosing a writing system was
    > praticality.
    > Quoting Peter Constable <>:
    >> Actually, I think actual adaptation of a script for use in other
    >> languages has less to do with its adaptability and more to do with
    >> things like prestige or regional importance by virtue of its use
    >> for some major language(s). E.g. Arabic script wasn't adopted for
    >> writing Turkish because the script was particularly adaptable for
    >> that language.
    >> Peter
    >> -----Original Message-----
    >> From:
    >> [] On Behalf Of John Hudson
    >> Sent: Friday, February 09, 2007 10:06 AM
    >> To: Eric Muller
    >> Cc: Lokesh Joshi; Richard Wordingham;
    >> Subject: Re: Query for Validity of Thai Sequence
    >> Eric Muller wrote:
    >>>> Successful writing systems tend to get adapted for multiple languages,
    >>> The term "successful writing systems" makes me nervous, especially with
    >>> the "tend to get adapted" part. Unless you define "successful" by "get
    >>> adapted" (in which case you have a tautology), the value judgment is at
    >>> best dubious. And anyway, your argument works equally well without
    >>> "Successful", so why go there?
    >> That's an entirely fair comment. I was writing quickly, but I
    >> suppose I was thinking of
    >> 'successful' in terms of demonstrated adaptability. Thinking of a
    >> script like Thai: this
    >> is a writing system that has already been adapted to a number of
    >> minority languages, ergo
    >> 'successful' in this sense, and it is reasonable to think that it
    >> might be adapted to
    >> others. In any case, the basic point is that one shouldn't make
    >> assumptions about how
    >> characters will be used in such adaptations.
    >> JH
    >> --
    >> Tiro Typeworks
    >> Vancouver, BC
    >> Marie Antoinette was a woman whose core values were chocolate,
    >> sex, love, nature and Japanese ceramics. Frankly, there are
    >> worse principles of government than that. - Karen Burshtein
    > -------------------------------------------------
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