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.

>
> 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.


xdt:anyAtomicType is a true subtype of xs:anySimpleType. It is a
supertype for all atomic types (only), whereas xs:anySimpleType
includes union types and list types (such as xs:NMTOKENS, xs:IDREFS
and xs:ENTITIES).


Cheers,
Dimitre Novatchev