Re: Stability Policy Update

From: Kenneth Whistler (kenw@sybase.com)
Date: Mon May 05 2008 - 15:07:44 CDT

  • Next message: Mark Davis: "Re: FYI: Google posting about U5.1"

    Richard Wordingham said:

    > ...
    > > * Strong normalization stability
    > ...

    The following is actually referring to Case Pair Stability,
    not Strong Normalization Stability:

    >
    > The condition, "More formally, for given versions V and U of Unicode, and
    > any two characters X and Y that are both assigned according to both V and
    > U::" could usefully be clarified by replacing 'two characters X and Y' by
    > 'two distinct characters X and Y'.

    I'm not seeing the useful clarification here. The conditions are
    trivially true for any uncased character if you want to test the
    edge condition and assume X = Y, since an uncased character casemaps
    to itself.

    > Readers may not assume that all parts of
    > a Unicode declaration are true, so the freedom to make a character lowercase
    > and add an uppercase partner might not be believed.

    What part of "A character that is not part of a case pair could become
    part of one if the new case pair is formed at the time of the
    addition of a new character to Unicode" is unclear or not to be
    believed?

    Here are a couple recent additions of a capital version of a case pair
    for a character that had been already encoded as of Unicode 4.0 or
    earlier:

    023D ; 4.1 # LATIN CAPITAL LETTER L WITH BAR

    03CF ; 5.1 # GREEK CAPITAL KAI SYMBOL

    So you already have an existence proof that such things happen.

    Now existence of such a change in the past is not proof that it
    *will* happen again in the future, of course. But no character
    encoding committee is going to say ahead of time exactly what *will*
    be encoded, because nobody knows that until proposals have been submitted,
    discussed, and ballotted.

    --Ken



    This archive was generated by hypermail 2.1.5 : Mon May 05 2008 - 15:10:19 CDT