Re: Questions on ZWNBS

From: Philippe Verdy (
Date: Fri Aug 08 2003 - 11:21:08 EDT

  • Next message: Philippe Verdy: "Re: Questions on ZWNBS - for line initial holam plus alef"

    On Monday, August 04, 2003 11:59 PM, Kenneth Whistler <> wrote:
    > The function I think you have in mind is not isolated display of
    > a combining mark, but rather trying to find a mechanism for
    > getting around the conformance strictures of the standard, to
    > get a combining mark to apply to a *following* base
    > character, rather than to a *preceding* base character.
    > Trying to use U+FEFF *or* U+2060 to do this would be inappropriate.

    I tried this sequence and it seems to have the correct behavior including
    for line breaking and word breaking:

    <some text>, <ZWSP, Combining Acute Accent, CGJ, A>, <B>

    It renders as some text, with a break opportunity before the ZWSP,
    a isolated accute accent combined with the following letter A, but
    this last combination depends on fonts (if they support CGJ to
    change the encoding order so that previous diacritics can combine
    in the same combining sequence as the next base character).

    This is quite tricky I admit, and I just wonder what is the correct
    usage of CGJ before a base character like Latin Capital Letter A.
    May be a distinct combining character could be used, but I
    wonder which one (CGJ is supposed to create some ligature
    between two normally distinct combining sequences each one
    containing at least 1 base character. There's been a recent
    discussion to use it also before a combining character and not
    only before a base character.

    If the initial break opportunity is undesirable, because the accented
    letter A is in the same word as the previous <some text>, then one
    can replace ZWSP (which is considered as white-space and thus a
    word separator) by a Word-Joiner control (preferably to the ZWNBSP
    U+FEFF whose usage in plain text is now deprecated if it is not used
    as a BOM, and preferably not a ligating format control which would
    have the undesirable effect of instructing the renderer to try using
    a ligated glyph for the combined sequence, and thus alter the
    semantic or appearance of the rendered text, where it was not
    intended that the combining mark should have any implied glyph
    relation with the previous base character)

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