Re: Generic base characters (was: Hebrew generic base)

From: John Hudson (
Date: Thu Jul 12 2007 - 20:03:34 CDT

  • Next message: Philippe Verdy: "RE: Phetsarat font, Lao unicode"

    Kenneth Whistler wrote:

    > Well, accumulating information about actual usage and existing conventions
    > strikes me as a useful exercise, particularly for font designers who may
    > end up having to include behavior in fonts to account for them. But how
    > would this end up being something defined *in Unicode*?

    > The standing way to "define a set of characters" in the Unicode Standard
    > is to invent a new property that defines that set. What property are
    > we talking about here? A binary property, Generic_Base? ....

    I was thinking in terms of something essentially informational and advisory: a list of
    Unicode characters that are known to be used as generic bases and layout engines should be
    prepared to merge in runs with following combining marks, as they currently do for the
    dotted circle. This list and appropriate comments could be appended to section 5.13
    Rendering Nonspacing Marks.

    I had not considered the idea that one might recommend that any of the geometric symbol
    characters might be used as generic bases. This might be a viable approach for a layout
    engine to take, but probably not for a font developer. I'm imagining that there are
    probably not more than ten generic bases that are attested, perhaps fewer, and that is
    something that is manageable from a font development perspective. They could easily become
    standard to any font that supports the dotted circle convention, since the same mark
    positioning could be applied to them all.

    I think my basic point in response to Philippe stands, regardless: the bases should be
    considered truly generic and not particular to the implementation of particular scripts or

    John Hudson

    Tiro Typeworks
    Gulf Islands, BC
    We say our understanding measures how things are,
    and likewise our perception, since that is how we
    find our way around, but in fact these do not measure.
    They are measured.   -- Aristotle, Metaphysics

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