RE: Query for Validity of Thai Sequence

From: Philippe Verdy (
Date: Fri Feb 16 2007 - 11:44:43 CST

  • Next message: Mike: "BOCU-1 spec"

    On 2/16/07, Richard Wordingham <> wrote:
    > Philippe Verdy wrote on Thursday, February 15, 2007 10:28 PM
    > > 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:
    > >
    > (...)
    > Peter Constable of Microsoft is well aware of these problems and was
    > endeavouring to ensure there would be no such problems in Windows Vista.
    > I don't know whether Microsoft have dealt with the problem the old rules
    > imposed for Pali and Sanskrit in Lao. Of course, Pali and Sanskrit need
    > missing consonants to be restored for Lao. I don't know how standard the
    > improper use of the unassigned code points in the Lao block is - I have
    > some surprises looking at the Lao fonts that provide the unencoded
    > consonants. I had expected the encoding to be basically Thai + 0x80,
    > that can't work for Indic NYA and YA.

    Please remember that OpenType is not just used and defined by Microsoft,
    there are also Apple, Adobe, Monotype, HP, and other wellknown font
    designers or rendering engine providers; this concerns not only Windows but
    all OSes, and also printer manufacturers (because they may use their own
    shaping engine, and their own page description language accepting OpenType

    (I'm curious about Canon, Brother and Epson because they have their
    rewritten version of the Postscript engine in some of thir entry models, to
    avoid paying the licence of the Adobe engine; some cheaper printers are
    using GDI interfaces to avoid including such complex engine in the printer,
    but this gets the complexity of rendering from Windows and those printers
    are not compatible with other OSes, and sometimes even not with several
    versions of Windows due to differences in the GDI implementation of Windows
    and no support in the driver to convert primitives of GDI absent in the
    printer. I don't like this strategy for cheap printers, and I much prefer
    that manufacturers adopt their own language description based on common
    industry standards rather than basing their design on a single OS).

    This archive was generated by hypermail 2.1.5 : Fri Feb 16 2007 - 11:47:38 CST