- From: Bijan Parsia <bparsia@cs.man.ac.uk>
- Date: Thu, 15 Nov 2007 02:21:34 +0000
- To: "Web Ontology Language (OWL) Working Group WG" <public-owl-wg@w3.org>
This is relevant to the Datatype issues. Qnames are defined in the XML Namespaces recommendation: http://www.w3.org/TR/REC-xml-names/ James Clark has a good (if old) primer: http://www.jclark.com/xml/xmlns.htm QNames are, in combination with namespace declarations, ways of writing down what Clark calls universal names. A universal name is a pair consisting of a namespace URI and a local name. Since the characters of a local name are legal URI characters (and obviously the same for the namespace URIs) you can concat them to form a URI. This is what the RDF/XML syntax does with *some* but *not all* qnames appearing in RDF/XML documents. That is, many, if not most, qnames appearing as element or attribute tags exist to abbreviate URIs. This is not true for such qnames as rdf:RDF or rdf:about (given the standard namespace mapping). This is easily seen if you consider that rdff:DF cannot map to the same universal name as rdf:RDF. QNames are *not merely abbreviation mechanism for URIs). This use is comparatively rare. (Hard to believe when coming from the RDF world. I know I was a bit shocked.) It is generally regarded as uncouth to do any of the following things: Create elements or attributes with universal names from a namespace not under your control. Coin URIs from URI spaces not in your control. While I generally don't really care about this uncouthness, it *is* a pretty standard point of coordination inside the W3C. The namespace name commonly associated with the prefix "xsd" "belongs" to the XML schema working group. So we have to exercise a bit of care before mucking with it. (We also have to take some care before inventing a new syntax for defining XML Schema types since, intra-W3C, that's XML Schema WG's job!) Currently, afaik, XML Schema does not provide URIs for datatype facets, although it does provide QNames. If we are going to make uris out of xsd:minInclusive, then we are *coining* those uris. They are easy to coin, but we're still doing something (and not merely reusing something XML Schema has done.) (Ok, I'm not 100% sure that they haven't coined those uris...this needs to be checked.) Similarly, if we use xsd:minInclusive *as an element or attribute* tag, and *don't* conform to the XML schema provided by the XML Schema working group, then, technically, we are redefining something in their namespace. So we need to check that they are cool with that. We probably need to review the Schema 1.1 documents to see if they affect us in any way. Cheers, Bijan. P.S. XML Schema 1.1 refers to the component designator WD: http://www.w3.org/TR/xmlschema11-1/#ref-scds
Received on Thursday, 15 November 2007 02:21:56 UTC