RE: Phetsarat font, Lao unicode

From: Philippe Verdy (verdy_p@wanadoo.fr)
Date: Mon Jul 09 2007 - 21:45:47 CDT

  • Next message: Peter Constable: "RE: Phetsarat font, Lao unicode"

    Peter Constable wrote:
    > Maybe you think a rendering implementation needs to re-order an Indic
    > vowel mark around an Arabic base letter; but my thought is that the
    > behavior for that kind of character interaction is simply not defined, and
    > I don't know of any user that would need it anyway, so this is a bit of a
    > pipe dream.

    That's my opinion too.
    So the Latin letter "x" should not be used for such interactions in Lao. It
    should only be instead a simple symbol, within the "Common" script, with a
    "S*" general category, directionally NEUTRAL, NOT mirrored (excluding arrows
    and parenthese-like punctuations), WITHOUT any case mapping, and NOT a
    decomposable compatibility character (like the squared letter-like symbols).

    There should be absolutely no special effect within normalizations, and with
    joining types. For full-text searching, such symbol should be ignorable
    using appropriate collation tuning (so, searching for Lao vowels should be
    possible using collation rules tuning that make symbols ignorable or treated
    like space).

    The symbol should also not be forming any ligation with nearby characters
    (so this should exclude box drawing symbols like the thin diagonal cross
    U+2573), and its glyph should not be context dependant (changed, positioned
    or resized according to modifiers). It should not break a single-script
    sentence within word breakers or line breakers, but treated like a word by
    itself.

    I may have forgotten other conditions for the simplest symbols (like the
    dotted circle symbol or the mathematical multiplication sign "") suitable
    for such use as a placeholder for a missing Lao consonnant. But using a
    Latin letter "x" is the worst option, given its many interactions.

    Candidate cross-like symbols that I can see suitable for such Lao use are:
    - U+00D7: the thin small multiplication sign;
    - U+2715 or U+2716: the thin or thick big multiplication crosses;
    - U+2717 or U+2717: the thin or thick vote checking crosses.
    And of course the dotted circle as seen in Unicode charts and the
    non-breaking space currently recommended as the invisible placeholder.



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