Re: What's the difference between xdt:anyAtomicType an

> > xdt:anyAtomicType is a true subtype of xs:anySimpleType.
>
> What derivation/inheritage/type is not a "true subtype"?


I used "true subtype" in set theoretic sense as "true subset".

A set A is a true subset of a set B if A is a subset of B and there
exists an element

b belonging to B that does not belongs to A.

In the case discussed, xdt:anyAtomicType is a subtype of
xs:anySimpleType and there exists a type (such as xs:IDREFS etc.) of
xs:anySimpleType that is not a subtype of xdt:anyAtomicType.


Cheers,
Dimitre Novatchev


On 7/3/05, Frans Englich <frans.englich@xxxxxxxxx> wrote:
> On Saturday 02 July 2005 23:17, Dimitre Novatchev wrote:
> > On 7/3/05, Frans Englich <frans.englich@xxxxxxxxx> wrote:
> > > Hi,
> > >
> > > I wonder, what is the difference between the xdt:anyAtomicType and
> > > xs:anySimpleType? It is a type(duh) and hence can code and definitions
> > > depend on it, but other than that, does it have any "effective" impact?
> > >
> > > Why does it exist? If it didn't exist, anySimpleType would have to
derive
> > > from the imaginary "itemType"; is that the reason?
> >
> > No. xdt:anyAtomicType is not identical (see below) to xs:anySimpleType.
> >
> > > Can the anyAtomicType be considered a "marker interface" for atomic
> > > values, but that it in practice is an anySimpleType?
> >
> > Any instance/subtype of xdt:anyAtomicType is an instance/subtype of
> > xs:anySimpleType but the reverse is not true.
>
> Yes, such kind of relationships emerges as soon one have different types.
>
> >
> > > In the XML.com article titled "The XPath 2.0 Data Model"[1] there's a
> > > small hint:
> > >
> > > "The Data Model document adds five new types to the 19 primitive types
> > > defined in the Part 2 Recommendation: [...] the xdt:anyAtomicType, an
> > > abstract type that plugs a newly-discovered architectural hole [...]"
> > >
> > > What was the architectural hole(or where can I read about it), and has
it
> > > any relation to my question?
> >
> > To represent the set of all types, whose instances are atomic (but not
> > list or union) types.
>
> Yes, good point, missed that. Except for that one(separating it from
> union/list types), does there exist any other reason to why anySimpleType
> could not be the direct base class of the atomic types?
>
> >
> >
> > xdt:anyAtomicType is a true subtype of xs:anySimpleType.
>
> What derivation/inheritage/type is not a "true subtype"?
>
>
> Cheers,
>
>                Frans