Re: GCGID for U+03B8

From: Asmus Freytag (
Date: Fri Oct 11 2002 - 23:36:37 EDT

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    At 08:50 AM 10/11/02 -0700, Doug Ewell wrote:
    >What is the correct IBM GCGID value for U+03B8 GREEK SMALL LETTER THETA?
    >Is it GT610000 or GT610002?
    >The Unicode 1.1 lists (UNICHP6B.TXT and UNICHP6C.TXT) are inconsistent
    >in this regard. Some entries, even within the same file, show GT610000
    >while others show GT610002. The tables printed in Unicode 1.0 book are
    >the same.
    >IBM has a Web page containing many PDF charts of code pages, and they
    >have the same problem: some show one GCGID for U+03B8, others show the
    >other one.

    Wouldn't you be able to tell by the shape associated with the GCGID?

    >I suppose this might have had something to do with confusion over U+03D1
    >GREEK THETA SYMBOL, but that character (a glyph variant of U+03B8) has
    >been in Unicode since 1.0. Was there some dispute at that time over the
    >preferred glyphs for U+03B8 and U+03D1? I remember that they were
    >swapped in Unicode at one point. Was the inconsistency in GCGID a
    >precursor to the decision to swap glyphs?

    They were swapped in Unicode 3.0 / second edition ISO 10646 to make the
    alphabetic sequence match the usage in typical Greek Text using an ordinary
    serifed typestyle, reserving the other code point (U+03D1) for the symbol
    as it shows in mathematical usage. (Some text fonts will use a form
    matching 03D1 for 03B8, but that's OK - those fonts are fully usable for
    text, just not for math).

    Historically, as far as I can tell, this relates to the fact that SC2 has
    documented its 8-bit character set standard with sans-serif type style(s)
    but 10646 and Unicode are using a serifed type style for the representative
    glyphs. Sans-serif fonts often contain the straight theta instead of the
    loopy one. As long as (small) character sets were only intended for text
    usage, any theta will do - Unicode and 10646 must be usable for both text
    *and* technical notation(s). That's where precise choice of representative
    glyph begins to matter. (The same is true for 0061 showing a hooked lower
    case a in distinction to the round lower case a for IPA. A font for non-IPA
    usage is free to use either form for 0061, but a font that needs to support
    or at least enable IPA usage is limited to the hooked form.).

    >Any ideas? (It's probably best not to ask why I am paying attention to
    >GCGIDs in the first place.)

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