Re: Defined Private Use was: SSP default ignorable characters

From: Peter Kirk (
Date: Wed Apr 28 2004 - 14:12:22 EDT

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

    On 28/04/2004 08:14, Language Analysis Systems, Inc. Unicode list reader

    > ...
    >There's been a lot of discussion of the PUA in this forum over the time
    >I've been on it, but I don't think I've heard anyone make the following
    >If you're using the PUA outside a closed system, you're not using
    >The PUA is intended for the internal use of applications (or groups of
    >applications), or for interchange between applications by private
    >agreement of all parties involved. ...

    This is not quite right. From TUS section 15.7,

    > 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.

    Note the last word. The private agreement is not supposed to be between
    all parties, including software developers. It is supposed to be between

    >... Writing a document in Microsoft Word
    >using some exotic script that doesn't have plain-vanilla behavior
    >violates this because Microsoft Word isn't a party to the private
    >agreement. ...

    Software developers, or applications, are not supposed to be party to
    the agreement between *users*. While applications are of course not
    obliged to support the PUA, if they choose to do so there should be no
    expectation that they are party to any agreement. And so a group of
    users with a private agreement can reasonably assume that software which
    supports the PUA in general supports their particular agreement.

    Of course applications may choose to support the PUA only with default
    character properties. But that is a separate issue.

    Peter Kirk (personal) (work)

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