Re: Unicode Stability

From: Peter Kirk (
Date: Thu Mar 03 2005 - 04:34:24 CST

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    On 03/03/2005 08:16, Doug Ewell wrote:

    > ...
    >Okay, hold on a minute. I'm being quoted out of context. My original
    >statement was:
    >"'Stability' in a standard does not mean that the standard never
    >changes. It means that, as much as possible, it does not change in a
    >way that causes existing implementations or data to break."
    >Since I wrote that on Tuesday, Peter Kirk has quoted it at least twice,
    >but *only the last part* -- not the part where I qualified it with "as
    >much as possible," and not the all-important part where this type of
    >practical stability is contrasted with absolute immutability.

    Doug, I am sorry for misquoting you. In the past I have got into trouble
    on this list for quoting too much, so I abbreviated your definition to
    what seemed relevant in the context. But I accept that I abbreviated too

    My whole point was to explore what does come within your caveat "as much
    as possible". Is it in fact possible to disunify two characters without
    having to invoke this caveat? Several people have suggested that it is
    not, that disunification necessarily "causes existing implementations or
    data to break" and so can be reconciled with stability only by "as much
    as possible", i.e. accepting some compromise of stability to meet a
    practical need. I suggested that there was an alternative method of
    disunification using variation selectors which made this more ideal
    stability possible - and which therefore made disunification by adding
    characters a breach of your stability definition because there is an
    alternative which does not "cause existing implementations or data to
    break". But, as Asmus has pointed out, variation selectors do not solve
    all of the problems, although in some cases (qamats qatan might have
    been one, if it wasn't for the technical problems with using variation
    selectors with combining characters) they might help to reduce the
    otherwise inevitable compromise of stability.

    Peter Kirk (personal) (work)
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