- From: <noah_mendelsohn@us.ibm.com>
- Date: Wed, 28 Jun 2006 19:15:20 -0400
- To: Harry Halpin <hhalpin@ibiblio.org>
- Cc: mark.birbeck@x-port.net, www-tag@w3.org
Harry Halpin writes: > This could be done by using a different character other than > ':', or *by saying that element and attribute names that use > ':' * are QNames, but CURIEs work for *attribute values that > use ':'*. Again, this might break something, not sure. Well, I think this might have been a better option some years ago than it is today. XML Schema was among the first widely deployed Recommendations to use QNames in attribute values, and indeed to define the type that allows users to put QNames in attributes or elements of their own. You might look back and say "mistake", but it's important to realize that in XML Schema in particular there's a non-trivial connection between the names of elements and the contents of some attributes. When you say in XML schema: <xsd:sequence> <xsd:element ref="pref:local"/> </xsd:sequence> the content of that ref attribute is naming an element! So, using QNames to do it wasn't some completely arbitrary choice, it was making references to elements symmetric with the naming of those elements. Schema then chose to use the same mechanism for all of it references, using QNames to refer not just to elements, but also to types, named model groups and the like. While your proposal above makes architectural sense in isolation, it's also true that there were some good reasons for the choice made in the XML schema language. Once you name things like elements with QNames, it's reasonable to expect that people will want to refer to them with QNames. IMO, if we really wanted prefix:local to mean concat(uriOf(prefix),local)), then that convention should have been enforced for element names as well as for references to them. For better or worse, I think the cat left the bag when Namespaces 1.0 was published. (Yes, it's also true that for each entity named by a QName there should be a corresponding URI, but that's a requirement for element names as much as for attribute content.) -------------------------------------- Noah Mendelsohn IBM Corporation One Rogers Street Cambridge, MA 02142 1-617-693-4036 --------------------------------------
Received on Wednesday, 28 June 2006 23:15:32 UTC