Re: 28th IUC paper - Tamil Unicode New

From: John Hudson (
Date: Mon Aug 22 2005 - 16:35:30 CDT

  • Next message: Alexej Kryukov: "Re: Historical Cyrillic in Unicode"

    Richard Wordingham wrote:

    >> GSUB tables don't handle the reordering in Indic languages. It's the
    >> responsibility of the OpenType Layout processor, e.g. Uniscribe.

    > So how do I get it to live up to its 'responsibility' to support an
    > Indic conlang living in the PUA? I'm not even sure that Burmese is
    > supported yet.

    > While it clearly looks like good practice to have a single per-script
    > definition of necessary re-orderings, in practice it is very
    > inconvenient if the user (or system administrator) cannot update the
    > definitions. For example, Microsoft has little incentive to modify
    > Uniscribe to treat independent Devanagari vowels as consonants (or, to
    > be pedantic, consonant-vowel ligatures).

    If you want something supported, you have to take it through the standards process and get
    it approved as part of Unicode or another standard that the software company in question
    is committed to supporting. If the behaviour you want to see for Devanagari becomes part
    of Unicode's processing requirements for that script, then you can expect Microsoft to
    support it.

    A shaping engine has no 'responsibility' to support an Indic conlang living in the PUA,
    because the shaping engine has no way of knowing that a string of PUA codepoints is text
    in an Indic conlang.

    The very nature of the PUA effectively makes it a dead end for most language processing,
    unless you have a very simple script in which there is a one-to-one correspondence between
    characters and glyphs and simple sequential, left-to-right display. Shaping engines simply
    don't know what to do when you pass them a PUA codepoint, because it could be *anything*.
    This is why using non-standard, PUA codepoints for any language processing is such a bad idea.

    John Hudson

    Tiro Typeworks
    Vancouver, BC
    Currently reading:
    Lords of the horizons, by Jason Goodwin
    Dining on stone, by Iain Sinclair

    This archive was generated by hypermail 2.1.5 : Mon Aug 22 2005 - 16:36:39 CDT