Re: AA versus TALL AA

From: Michael Everson (
Date: Sat Mar 25 2006 - 11:22:24 CST

  • Next message: Richard Wordingham: "Myanmar Redesign Proposal (was: AA versus TALL AA)"

    At 14:06 +0000 2006-03-25, Richard Wordingham wrote:

    >Is this a Unicore escape?

    It was a typo on Ken's part. Discussion of this proposal with members
    of the UTC is fairly intense. I don't personally have the time or
    energy to get into too much of it on this list.

    >>This results from Everson's advocated solution, disunifying
    >>based on glyph shape.
    >> Encoding Rendering rule Reading rule
    >>Burmese: xa yA a --> {a} {a} --> a
    >> A --> {A} {A} --> A
    >>S'gaw Karen: xA yA A --> {A} {A} --> A
    >For Burmese, isn't this akin to using undotted 'i' (U+0131) in the
    >English word 'fish' because good typography leaves it ligated and

    No. That's a matter of taste.

    >The motivation for the tall form in Burmese seems to be to
    >distinguish consonant plus vowel from another consonant.

    This is pindeed the explanation for the Burmese practice (it's
    specified in an 1889 grammar of Burmese on my desk for instance).
    Short AA was preferred but was ambiguous with some contexts so TALL
    AA is mandated for those. But in many instances the short AA is used
    again when a medial is used with letters that otherwise take TALL AA.
    And then there are differences between Burmese and Mon, where Mon
    regularly uses TALL AA with PHA, though modern Burmese doesn't. (An
    1840 Burmese Bible does, however.)

    >I guess that one reason for Sgaw Karen dropping the round form was
    >that it was simpler to teach a single glyph shape.

    I guess that guesses like this are worth less than research. Anyway
    it's unrelated to the issue at hand. It is proposed to disunify TALL
    AA from AA because (1) adding a non-variable TALL AA for Karen use
    would introduce ambuguous encounters

    >Moving slightly eastwards, the decision here sets a precedent for
    >the Lanna script.

    The decision here hasn't been taken yet. It is proposed, and I favour
    it. Martin and I worked on Lanna before we went to Yangon, however,
    and had already decided that Lanna would require an AA and a TALL AA.

    >The practical rules may also be quite complex, though I stopped
    >worrying when I was advised that a solution using variation
    >selectors could leave the glyph choice in their absence to the

    Variation selectors are pseudo-coding. I despise them. You might
    propose to use variation selectors to indicate casing in Latin
    because, of course, "a" and "A" are "really" the same character.

    In scripts like Lanna and Myanmar, where it is really *not* possible
    to contextually select the display, the only sensible thing is to
    encode both AA and TALL AA and let users use the one they want when
    they want it. Keyboards in Myanmar currently have keys for both AA
    and TALL AA. It's derived from typewriter practice, but it means that
    people distinguish them. (Whether they are good at spelling is
    another matter, but then many English speakers don't know when to
    capitalize letters either.)

    OK, that's enough for me. Back to the grindstone.

    Michael Everson *

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