Re: PUAs properties (was: What is the principle?)

From: Philippe Verdy (
Date: Tue Mar 30 2004 - 20:19:34 EST

  • Next message: Michael Everson: "RE: What is the principle?"

    From: "Kenneth Whistler" <>
    > > Users can define only those properties which the
    > > software that they are using allows them to define. Your argument here
    > > completely ignores the distinction between users and software
    > > developers.
    > No it doesn't. I am well aware of the distinctions between end
    > users, application developers, OS platform developers, and
    > basic library implementers. I have, at one point or another,
    > been in all of those shoes.

    Would adding those alternate properties in PUA fonts violate Unicode? I don't
    think so because it is application-specific, but this does not mean that no
    standard can be developed here to carry those information that Unicode refuses
    to integrate in its standard.

    In fact, your argument to maintain a strong default LTR directionality for PUAs
    means that people have no other choice than developing psecific applications
    that can bypass this interoperability problem (also because any application that
    would use a distinct default for PUAs would, in my opinion, violate Unicode).

    So why not adding character properties tables in fonts, and get something that
    would please users of those PUAs as they could now start interchanging
    documents, not by using only Unicode encoded plain-text with PUAs, but by
    agreeing simply on the best font to use to render or parse a document using
    those PUAs. OpenType tables in fonts are extensible, and if such standard table
    formats were specified, they could finally be recognized in various renderers to
    get what users want. Or used in text parsers if instructed to get the properties
    tables from a font (even if this is not for rendering purpose).

    An alternative could be to develop a compact interchange format for properties,
    and to make this file format optionally embeddable directly in fonts (so that it
    becomes easier to perform text handling without rendering).

    Saying that something is private and requires people agreement does not forbids
    the developement of a new standard. After all, all standards are born first by
    private mutual agreement, and the adoption of the same agreement by more
    interested people.

    Other interchangeable Unicode properties formats are also needed, notably for
    the localized collation tables. Will Unicode work to prohibit such developments?
    It would be unfair for those that want to use the freedom given to them with
    PUA. Private use does not mean that this can't be interchanged. It's just that
    it has no standard behavior defined by Unicode itself, and Unicode makes this
    statement of allowing PUAs as a guarantee offered to users to allow such
    separate standard development without conflicting with other Unicode works.

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