Re: Defined Private Use was: SSP default ignorable characters

From: Peter Kirk (peterkirk@qaya.org)
Date: Thu Apr 29 2004 - 04:14:39 EDT

  • Next message: Peter Kirk: "Re: Defined Private Use was: SSP default ignorable characters"

    On 28/04/2004 16:04, Kenneth Whistler wrote:

    >>>Oh? How does the existing PUA fail to support a picture font adequately?
    >>>
    >>>
    >>>
    >>>
    >>My point is that, according to what Ken has written, the PUA can be used
    >>for a picture font only if not only the end users but also the software
    >>developers have come to a specific agreement about that picture font and
    >>the identity of each character in it.
    >>
    >>
    >
    >Nonsense.
    >
    >

    I'm glad to hear it! :-)

    >
    >
    >>He seemed to reject my suggestion
    >>that developers might sensibly support the PUA apart from such specific
    >>agreements with end users, by supporting default character properties
    >>for each PUA character and allowing the glyph to be specified in the font.
    >>
    >>
    >
    >It is my understanding that that is precisely what most rendering systems
    >do right now with PUA characters.
    >
    >

    Again, I am glad to hear it, and I am glad to hear that you seem to
    think is sensible behaviour. For this is really all I was asking for, at
    this point. I had obviously misunderstood you when I thought you were
    saying that this was an abuse of the PUA because the application is not
    a party to the private agreement about the interpretation of the PUA
    characters.

    >What you *cannot* expect a generic system to do, for example, is
    >support casing rules for a bicameral script that you have
    >defined a bunch of characters for in PUA code points. For *that*
    >kind of behavior, you have to have an "agreement" with the implementing
    >software, because it represents behavior beyond the "default character
    >properties for each PUA character". ...
    >

    Understood.

    >...
    >
    >
    >>Agreed, but only if the PUA works in the kind of way which you and I
    >>envisage. If it works as Ken envisages, which is very close to saying
    >>that it doesn't work at all, you would be wrong to expect any support
    >>for any of the properties you have listed, because applications should
    >>not even try to support PUA characters of which they have no specific
    >>knowledge.
    >>
    >>
    >
    >What seems to be repeated, deliberate misrepresentation of my
    >position on this is getting rather tiresome.
    >
    >

    Please, Ken, my misunderstanding is not deliberate. I may be stupid, but
    I am not being deliberately obstructive. I am grateful now for your
    clarification, although I still don't see how it is consistent with your
    earlier insistence that "users" include software applications in this
    sentence from TUS section 15.7,
    http://www.unicode.org/versions/Unicode4.0.0/ch15.pdf:

    > Private-use characters are assigned Unicode code points whose
    > interpretation is not specified by this standard and whose use may be
    > determined by private agreement among cooperating users.

    But I am not expecting further clarification now.

    -- 
    Peter Kirk
    peter@qaya.org (personal)
    peterkirk@qaya.org (work)
    http://www.qaya.org/
    


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