Re: Greek characters in IPA usage

From: Asmus Freytag (
Date: Fri Aug 14 2009 - 12:39:15 CDT

  • Next message: Michael Everson: "Re: Greek characters in IPA usage"

    I think Julian makes a good point. There has been a gap in the
    character-glyph model.

    Now that the role of variation selectors has become clearer and more
    widespread (IVD), it makes sense to identify places where it belongs,
    but hasn't been used. In both IPA and mathematical usage, there are
    characters which must not be rendered with some of the otherwise normal
    choices of glyphs, lest the notation become ambiguous. It's the "a" with
    handle at code point 0041 for IPA; for math if would be ensuring the
    looped form of "phi" at 03C5, so that it contrasts to 03D6, etc.

    So far, the official recommendation has simply been "don't use a font
    that's unsuitable for IPA (resp. unsuitable for math)".

    This requirement is only known to the author of the text, so such text
    can only be created in those rich text formats where control over the
    font choice rests with the author of the document. (Which, notoriously,
    is not the fact for HTML, a rich text format where font substitution
    somewhere between author and reader is more than likely).

    With the use of variation selectors, in contrast, it would be possible
    to encode the requirement for the restricted range of glyphic variation
    in the text. If a font supported the variation sequence, it would be
    used, otherwise the software would be able to substitute a font that
    supported it, or was otherwise known to provide a suitable glyph.

    For mathematics, the problem is perhaps less acute, since it's already
    necessary for software (or document formats) to split the text into math
    and non-math runs of text in many instances, because the formatting and
    layout rules differ. But wherever individual variables are cited in the
    accompanying text such identification might break down, and variation
    selectors might still be useful.

    Furthermore, the use of variation selectors would enable a larger set of
    fonts to serve mixed use, wherever certain notations have arbitrary
    glyph requirements that only partially overlap with the natural glyph
    range for a given character. (There'd still be enough fonts that remain
    unsuitable for notational purposes, but there'd be a larger choice of
    "safe" plaintext fonts).

    By adding a few variation selectors, the encoding model could be made
    complete. Alternate character codes would cpntinue exist whenever
    symbols/entities are used in contrast with each other. Variation
    sequences would be used when the glyph-range is restricted for
    notational purposes. By adding a variation sequence, the piece of
    semantic information that a character is intended for notational purpose
    and thus requires a restricted glyph range can be made explicit in the
    (plain-)text and no longer has to be implied by styling information
    (font selection).


    On 8/14/2009 8:22 AM, Julian Bradfield wrote:
    > Don't forget there's chi, as well as beta and theta.
    > As a hard-core IPAist, who type my phonological papers in a text
    > editor using a single Unicode font (the necessary font switches for
    > print being LaTeX markup), I would naturally prefer to have separate
    > characters for IPA chi, beta, theta.
    > However, I do have some qualms about this: why do I not also need a
    > separate ipa "a" - I might be using a font in which the normal "a" is
    > actually ɑ-shaped! Indeed, really I would like separate codepoints for
    > all IPA letters - but we know that would fail dismally in practice,
    > even had it been implemented from the start.
    > Given the situation as it is, I support the idea of variation selectors.

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