RE: [xml-dev] Meta-somethingorother (was the semantic web mega-permathread thing)

["Joshua Allen" <joshuaa@microsoft.com>]

> I'm not sure I ever have written such a schema. I think I tend to
> make what you're calling properties element names rather than a
> complete separate element or node, but maybe I'm not quite following

Yes, that's OK.  I think using element name (or attribute name) is the
only way that RDF ever models property names anyway.

The idea is, in a particular schema, do you make sure that property
names are modeled in a predictable manner, and that all properties
actually *have* a property name?

The acid-test is, if an outsider looked at your XML, and you told him
what the general rules of your syntax were (without element names,
attribute names, etc); could he enumerate which things are property
names, and which things are property values (or object names)?

> models can be applied to the same document. Unlike RDF's canonical
> triples/subject-predicate-object model there is no one data model for
> XML.

Well, RDF "data model" is only slightly more constrained than XML, and
applications are welcome to use internal data models rather than that
implied by XML or RDF.  By XML "data model", I mean:

a) you have a tree of nodes, and all nodes must have a name
b) a node may contain other nodes, literal values, or nothing
c) node values may reference other nodes

RDF has some extra requirements, but not enough that I would think of it
as being a straight-jacket.  You still have to decide what to do with
the data; the only difference is that you have a couple more hints from
the data.