Re: Defined Private Use was: SSP default ignorable characters

From: Kenneth Whistler (
Date: Thu Apr 29 2004 - 14:51:45 EDT

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    Peter Kirk continued:

    > >>... If you want to abolish the PUA,
    > >>
    > >>
    > >
    > >I do not, and have no idea why you are imputing that to me, except,
    > >I suppose, because I have been speaking against your position.

    > >
    > You did write the following, in response to Dean:
    > >>Currently, I view the PUA as practically a wasteland, unusable for even
    > >>for the most basic research work.
    > >>
    > >>
    > >
    > >A wise decision, all in all.
    > >
    > >
    > Maybe "abolish" was not the right word as presumable aboition would
    > breach stability agreements. But you do seem to want to "deprecate" it,
    > or at least to strongly discourage its use,

    Not really.

    That particular response to Dean was tongue-in-cheek, in case you
    missed it. I suppose I should just refrain from attempts at humor
    in responses, as they seem to get interpreted by some people as
    literal statements.

    So here is that comment, restated and explicated in full.

    Dean Snyder has come to the conclusion that use of the PUA is
    problematical for the kinds of purposes he envisioned putting it
    to, because support for custom properties is nonexistent in
    easily available software, because support for display is spotty,
    because ensuring that other people share the same conventions
    as he might want to define is difficult, because he
    or the other scholars he might want to work with may lack the
    expertise and/or funds to accomplish the custom programming they
    might need to do to use a PUA encoding effectively, and because
    the time involved in getting the PUA to work for his research
    might better be spent doing something else, including working
    through an actual standardization proposal for the script(s)
    he might be interested in.

    I *agree* with those assessments.

    Using the PUA for encoding some scholarly text should be a matter
    of *last* resort, when no other option is really available. And
    then the person who resorts to that should be prepared to use
    the PUA with minimal generic support and with plans to export/convert
    to other formats for particular kinds of processing and/or
    rendering that they may require. And they should be prepared
    to get their hands dirty with some programming to accomplish
    what they need to do.

    The PUA is basically a "wasteland", as Dean indicated. It is a
    range of 137,468 code points that are provided for people to
    do with what they will. Caveat emptor. It is silly to expect
    that what one person might decide to do with them will not run
    into problems with what somebody else might decide to do with
    them -- after all, their interpretation is *deliberatly* not
    standardized -- that's the nature of "private use".

    > except apparently for purely
    > internal use within one company, which is outside the scope of the standard.

    I think you may have some serious misapprehensions about what
    "use within one company" means these days in software
    development. Software these days is massive, distributed,
    and modular. The "private agreement" I have on some PUA
    character's use may be shared publicly with some other group
    developing some other piece of software. It may involve harmonizing
    a decision on private use with private use defined by some *other*
    company's software, without that decision ever rising to the level
    of end-user visibility. Such issues are *not* outside the
    scope of the standard. We depend on a common understanding of
    what PUA code points are and how they might be used, as defined
    by the standard. The particular intepretation that I might
    use in a particular piece of software *is* outside the scope
    of the standard, but that isn't correlated with whether that
    usage is within one company or not.

    As it happens, one of the major uses to which PUA code points are
    actually put in major software today is in cross-mapping East
    Asian code pages. And in such cases there are implicit "private
    agreements" between the company that might define such a
    cross-mapping involving an East Asian code page and another
    company that may use such a cross-mapping or which may have to
    provide a conversion table which emulates the same cross-mapping.
    That is a *very* common situation in software development today.


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