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

From: Philippe Verdy (
Date: Tue Mar 30 2004 - 14:28:31 EST

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    From: "Dominikus Scherkl (MGW)" <>
    > > >They do not. A user of PUA characters is free to define the
    > > >whole range of PUA characters as consisting of strong R-to-L
    > > >characters and implementing accordingly. ...
    > >
    > > This is not true! Users can define only those properties which the
    > > software that they are using allows them to define.
    > I would expect any application to allow _all_ properties to be
    > defined by the user for each and any PUA charakter.
    > If not so, it's a bug in the application!

    Certainly NOT a bug, a limitation possibly, but how would you define the user
    properties associated with a font that contains all its glyphs in PUAs?

    Can a OpenType font specify a table of character properties to enable correct
    rendering behavior of plain-text files containing PAUs that are said to be
    rendered with a specific font redefining these default PUA properties ?

    I looked into OpenType specs, and there's apparently no standard table format
    defined that would allow describing those PUAs. It's not a bug, but clearly a
    limitation too.

    Is there some alternate font formats (other than OpenType/TrueType) where such
    properties tables can be defined, notably the BiDi behavior, and the line
    breaking opportunities, or (why not?) some case foldings (if one wants for
    example to render some styles like small caps with the same PUA font) ?

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