Re: markup on combining characters

From: Peter Kirk (
Date: Tue Sep 07 2004 - 18:06:41 CDT

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    On 07/09/2004 23:56, Philippe Verdy wrote:

    > From: "Peter Kirk" <>
    >> By the way, any suggestion of making the QQ distinction with markup
    >> is ruled out by the principle recently expounded on the main Unicode
    >> list that separate markup cannot be applied to combining characters.
    > Isn't this need of allowing separate markup on combining characters
    > addressed by the current proposal to encode a invisible base character
    > (IBC), so that markup can be applied to a non defective combining
    > sequence?
    > I understand that this proposed new character would more likely be
    > used to allow rendering isolated combining marks, without needing to
    > encode their spacing variant, but the sequence <IBC,combining mark>
    > (now possibly enclosed in markup) could become a candidate for
    > possible ligaturing by preceding it by a ZWJ, or for word-wrap
    > exclusion with a leading WJ...
    You mean, you would represent a black e with a red acute accent as
    something like "e", ZWJ, "<red>", IBC, acute, "</red>"? That looks like
    a nightmare for all kinds of processing and a nightmare for rendering.

    The proposed INVISIBLE LETTER is supposed to be a *spacing* character
    which can carry a combining mark. The idea of making it non-spacing by
    joining with ZWJ to some other character horrifies me. I can see an
    argument for a separate non-spacing invisible letter, especially as a
    base character for spacing combining marks when no extra space is needed
    before them, but even that sounds quite horrifying as a way of putting
    separate markup on combining marks.

    Peter Kirk (personal) (work)

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