[Bug 2046] R-181 (Datatypes): clarify equality and identity of lists

http://www.w3.org/Bugs/Public/show_bug.cgi?id=2046





------- Comment #5 from cmsmcq@w3.org  2007-10-14 18:10 -------
At the ftf meetings of October 2007, the XML Schema WG discussed
this issue together with the XML Query and XSL WGs (in the context
of a discussion of bug 3243).

QT vigorously argued that the direction outlined for this issue in the
comments on bug 2045 and bug 2046 should be reversed and that XSDL
should align with QT in treating the difference between atomic values
and singleton lists containing those atomic values as a purely
metaphysical distinction.  After discussion, we agreed to instruct the
editors to prepare wording proposals for Datatypes (bug 2046) and
structures (bug 2047), in which it's made clear that for XSDL purposes
singleton lists are not distinguished from the atomic values which are
their list items.  As far as we could tell, this would affect only
identity constraints, since we couldn't think of any way to construct
an enumeration or a fixed value constraint which would involve
comparison of an atomic to a singleton list.  (Further thought shows
that a union of a pattern-restricted integer with a list of
differently pattern-restricted integers would allow tests to be
constructed.)

These wording proposals will, we hope, be useful in achieving
agreement on the correct technical direction.  (That is, they are
phase-1 proposals, not phase-2 proposals.)  Before we make any final
decisions, we should perform some due diligence to see if existing
processors all do the same thing in these cases (and what that thing
is) and whether existing schemas seem likely to be affected.

Received on Sunday, 14 October 2007 18:10:19 UTC