RE: Unicode's Mandate

From: Peter Constable (
Date: Sat Mar 05 2005 - 11:22:55 CST

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    > From: []
    > Behalf Of Jon Hanna

    > > I would love "flexibility" like an "eXtensible Glyph Format".
    > Sounds like an interesting idea.

    No, it sounds completely meaningless.

    A glyph is a graphic object; depending on your terminology, it is either
    a concrete object, for which the term "glyph image" is also used, on
    abstract object corresponding to a set of glyph images with a common
    identity. A "format" means some means of representing information -- in
    this case information about a glyph. So, unless this is supposed to be a
    format for representing meta-information about abstract glyphs, it must
    mean a format for representing glyph images. Such formats exist: the
    various outline formats, such as TrueType outlines, or pixel formats.
    What's to extend? Are there glyph images that cannot be represented
    using TrueType outlines? No, there are not (and won't be as long as
    writing is done on surfaces rather than in three-dimensional space). The
    only likely extensions are for things like colour of elements within a
    glyph, and such extensions happen as significant innovations of a
    technology such as the TrueType spec; there's no need for a framework
    for arbitrary extensions of formats for representing glyphs by end users
    or in derivative specifications.

    I suppose if he was referring to a format for representing
    meta-information about abstract glyphs, then extensibility could make
    sense since there may be all kinds of arbitrary information about a
    glyph that someone may wish to record. But I really doubt this is what
    Doug is talking about.

    Most likely, Doug had in mind something that the name does not really
    reflect. Something like an extensible document format in which text is
    represented in terms of glyph identifiers. Such a thing exists. It's
    called "Portable Document Format" -- "PDF" for short.

    Peter Constable

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