[Bug 17477] New: [DM 3.0] Definitions of xs:untyped, etc

https://www.w3.org/Bugs/Public/show_bug.cgi?id=17477

           Summary: [DM 3.0] Definitions of xs:untyped, etc
           Product: XPath / XQuery / XSLT
           Version: Last Call drafts
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Data Model 3.0
        AssignedTo: ndw@nwalsh.com
        ReportedBy: mike@saxonica.com
         QAContact: public-qt-comments@w3.org


In section 2.7.2 of XDM we give a brief definition of the types xs:untyped,
xs:untypedAtomic, and xs:anyAtomicType.

At the end of the section we say "A schema for these types is provided in C
Schema for the Extended XS Namespace."; however, this only applies to the last
two types listed (xs:dayTimeDuration and xs:yearMonthDuration).

We should say that when the implementation supports XSD 1.1, the XSD 1.1
definitions of the types xs:anyAtomicType, xs:dayTimeDuration, and
xs:yearMonthDuration supersede those in the XDM specification.

We should also say a little more about the types xs:untyped and
xs:untypedAtomic. For example, the specification of deep-equal() depends on
knowing whether these types are simple or complex, and if complex, what their
variety is. (I imagine xs:untyped is a complex type with mixed content, but I
don't see anything that says this explicitly). Ideally we should give a
property tableau for these types in the same style as XSD (see for example
http://www.w3.org/TR/xmlschema11-1/#builtin-ctd). Or perhaps we could say that
the properties of xs:untyped are the same as those of xs:anyType, except for
the base type and the name.

Finally, we say "No predefined types are derived from xs:untyped.", and the
same for xs:untypedAtomic. I think we should also say that no user-defined
types can be derived from these types. (It's fairly obvious that we provide no
mechanism to derive user-defined types from these built-in types, but some
implementors provide programmatic ways to construct new types and for
completeness we should ban this, as the semantics are not well defined.)

XSD 1.1 prohibits derivation from xs:anyAtomicType by restriction, union, or
list, and we should do likewise for implementations using XSD 1.0.

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Received on Wednesday, 13 June 2012 08:00:59 UTC