xml-dev - XLink a special case in the self-describing Web?

["Steven R. Newcomb" <srn@techno.com>]

Please correct me if I'm wrong about any of this.

(1) XML Namespaces do not provide a way for a single element to
    conform to an element type in each of several schemas.  Therefore,
    there is no way for a single element to be recognized as
    conforming to both the X:Foo and the Y:Bar element types.

(2) XLink is now just attributes; the element type can be anything.
    This permits a single element to be recognized as an XLink and as
    whatever else it may be.  (Whatever else it may be, it may still
    only be one element type in one single namespace, as far as I
    know.)  This is a kind of sleight-of-hand: XLink elements are
    still XLink elements; we still expect certain combinations of
    attributes to appear in certain contexts and not in others.

So, if my above understandings are correct, I tentatively conclude
from this that XLink is not a namespace or a schema in the usual
sense, because, among all of the kinds of element definitions that are
possible, only the XLink element types are, de facto, exempt from the
"one element, one element type name in one semantic space of element
type names" rule.

Can anybody create sets of attributes, just as has been done with
XLink, that will constitute a semantic space, and thus effectively
have elements identify themselves as conforming to certain element
types without requiring that the generic identifier be used to
identify the element type?  If anybody can already do this, is this a
methodology to which XML Schemas can provide validation services, by
checking to see whether all of the attributes have been used in
syntactically valid ways?  If so, how?

-Steve

--
Steven R. Newcomb, President, TechnoTeacher, Inc.
srn@techno.com  http://www.techno.com  ftp.techno.com

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