RE: Merging combining classes, was: New contribution N2676

From: Peter Constable (
Date: Wed Nov 05 2003 - 18:13:30 EST

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    > -----Original Message-----
    > From: []
    > Behalf Of Peter Kirk

    > But I am not sure that this get-out clause should
    > be applicable to a process which claims as its very essence "to
    > correct positioning of nonspacing marks" but actually supports only a
    > particular arbitrary (non even canonical) order.
    > I would like to see this clause tightened up to say that a process
    > claims to interpret properly a particular sequence of marks must
    > interpret all canonically equivalent variants of that sequence
    > identically, with the exception of special modes to show the
    > character sequence.

    That can't happen unless Unicode gives some definition to "claims to
    interpret properly a particular sequence of marks", and that is not
    likely to happen any decade soon.

    > Arguably conformance clause C7 in fact states this, on the basis that
    > canonical equivalence is a part of character semantics:
    > > C7 A process shall interpret a coded character representation
    > > according to the character
    > > semantics established by this standard, if that process does
    > > that coded character
    > > representation.

    < a-acute > and < a, combining acute > are two different coded character
    representations. Software can be conformant if it interprets the former
    but not the latter. C7 and C9 were written explicitly to make sure that
    was possible.

    > It must
    > interpret a non-normalised variant

    Conformance does not obligate a process to interpret any coded character
    representation, no matter what other coded character representations it
    may interpret.

    Peter Constable
    Globalization Infrastructure and Font Technologies
    Microsoft Windows Division

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