Re: ct, fj and blackletter ligatures

From: Thomas Lotze (
Date: Tue Nov 05 2002 - 05:04:06 EST

  • Next message: John Cowan: "Re: ct, fj and blackletter ligatures"

    William Overington wrote:

    > Well, I suppose it depends upon what one means by a file format that
    > supports Unicode.

    In my reply, I understood by that term a font which both uses Unicode
    code points and employs Unicode control character mechanisms. Only in
    conjuction with these mechanisms does the policy not to encode alternate
    presentation forms and ligatures work well.

    > 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".

    What about Opentype with TT outlines?

    > Please note that
    > my sentence did have "if the font designer wishes people to be able to
    > have direct access to the ligature characters".

    Sure. My point was that talking about Unicode compliance only makes
    sense if you have both a Unicode compliant font and rendering engine.
    AIUI, in that case you don't need more direct glyph access than you get
    by Unicode strings including control characters.

    > Using Private Use Area code points [for ligatures] avoids conflicting
    > with the regular Unicode code points used for other characters.

    It does avoid conflicting with regular UVs. However, since Unicode is
    meant as a character encoding rather than a glyph encoding, it conflicts
    with the concept of Unicode. The comparison may be far-fetched, but
    encoding things that are not to be Unicode-encoded reminds me of
    so-called XML documents that have an opening and a closing tag and
    binary data in between. It's the same kind of defeating the purpose of a
    standard through a backdoor.

    > Yet, suppose that one has an advanced format font with a ct glyph
    > within it yet where the font does not provide a direct code point
    > access glyph, but only allows a ct ligature to be displayed using a
    > combination of computer hardware

    Why hardware? When talking about screen representations and file
    generation, no hardware has a say in the matter. (I could imagine a
    printer directly handling intelligent font formats, though.)

    > and software which supports the advanced font format. How
    > is one going to get that ct ligature to display if one does not have
    > access to that hardware and software combination?

    No problem. Either you find some way to access the glyphs by their glyph
    name or sequential position in the font rather than by code point, or
    you just have to live with the fact that in order to get some feature,
    you need software that provides it. Another comparison: this reminds me
    of ASCII graphics where one tries to get graphics effects without having
    graphical capabilities. It works to a certain extent but is a workaround
    at best.

    > Now certainly the attempt has
    > been made to trivialise the matter by reference to very very old
    > computer systems, yet here the problems arise with PCs manufactured in
    > 1999.

    What is the relevance of the hardware? Do I miss something here?

    > if people choose to ignore the
    > golden ligatures collection, then that is up to them and if people
    > choose to use the golden ligatures collection then that too is up to
    > them.

    Actually, I find your collection useful, but more from the angle of
    typography than from that of Unicode.

    > I have also had great enjoyment in preparing the golden
    > ligatures collection in that I have learned a lot about ligatures
    > which were used by printers in days gone by.

    I know that kind of enjoyment; typography is rather dangerous to other
    interests ;o)

    Cheers, Thomas

    Thomas Lotze
    thomas.lotze at            

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