Re: ct, fj and blackletter ligatures

From: John Hudson (
Date: Tue Nov 05 2002 - 10:14:29 EST

  • Next message: Edward H Trager: "Re: Special characters"

    At 02:18 11/5/2002, William Overington wrote:

    >Well, I suppose it depends upon what one means by a file format that
    >supports Unicode. The TrueType format does not support the ZWJ method and
    >thus does not "provide means to access unencoded glyphs by transforming
    >certain strings of Unicode characters into them".

    All three of the current 'smart font' formats are extensions of the
    TrueType file format. Structurally, the only difference between a TrueType
    font and an OpenType font is the presence of *optional* layout tables that
    support glyph substitution and positioning. Officially, the only difference
    is the presence of a digital signature.

    >I am unsure as to
    >whether, in formal terms, TrueType is "a file format that supports Unicode"
    >as it does not allow the ZWJ sequences to be recognized.

    Of course TrueType allows ZWJ sequences to be recognised. ZWJ is a
    character that can appear in Unicode text and in the Unicode cmap of a
    TrueType font. If a font does not contain a ligature for the sequence, or
    does not contain layout information to render the sequence as a ligature,
    the text is still processed according to the Unicode Standard, i.e. nothing
    happens. To say that a font only supports Unicode if it can process and
    render as a ligature every usage of the ZWJ character is foolish: every
    font would have to contain glyphs and substitution lookups to support every
    potential use of ZWJ in every possible
    That's even more moronic that saying that a font has to contain a glyph for
    every character in Unicode in order to support the standard. It simply is
    not true, and you're wrong. Again.

    John Hudson

    Tiro Typeworks
    Vancouver, BC

    It is necessary that by all means and cunning,
    the cursed owners of books should be persuaded
    to make them available to us, either by argument
    or by force. - Michael Apostolis, 1467

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