- From: Dave Beckett <dave.beckett@bristol.ac.uk>
- Date: Thu, 07 Feb 2002 14:25:54 +0000
- To: RDF Core <w3c-rdfcore-wg@w3.org>
- cc: Brian McBride <bwm@hplb.hpl.hp.com>
>>>Brian McBride said: > ... I also asked DaveB to look into the DC viewpoint > ... could you share the resulst with the list please. I asked the lead author of Expressing Qualified Dublin Core in RDF / XML http://dublincore.org/documents/2001/11/30/dcq-rdf-xml/ which is a Dublin Core Metadata Initiative (DCMI) standards-track document to comment on the datatypes issues that were being brought up. We've exchanged emails but not got really to a terse summary. I'm the lead editor of Expressing Simple Dublin Core in RDF/XML http://dublincore.org/documents/2001/11/28/dcmes-xml/ So the following is my opinion with my DC hat on, NOT an official view of the DCMI. In the notes below, the set of 15 elements is the DCMI is the Dublin Core Metadata Element Set (DCMES). 1. DCMI uses XML Namespaces for grouping concepts DCMI Namespace Policy http://dublincore.org/documents/2001/10/26/dcmi-namespace/ 2. DCMI will define only 1 term for a concept, in some namespace. So like for PRISM (also a DCMES in RDF/XML app) - DCMES will not define multiple versions of terms. 3. URIs for DCMI terms are constructed by appending the term name to the namespace URI for the term. See namespace policy document above. 3. DCMES already uses and recommends the following RDF/XML for writing simple DCMES property and value. <dc:title>title of thing</dc:title> and for RDF/XML expects the triple <thing> dc:title "title of thing" . to be emitted Plus <dc:title rdf:resource="URI"/> is allowed. Both may be used at the same time. 4. DCMI provides RDF Schemas at the namespace URIs of its terms So providing extra datatyping info for each term is possible. 5. DCMI expects xml:lang attribute to be allowed on XML <dc:title xml:lang="en">title of thing</dc:title> and the DCMI community wants to be able to get at that language value somehow. I strongly support this. I have been asked by some people in DCMI community how RDF models this and could not give an answer. 6. The DCMI has the idea of "encoding schemes" for expanding on the value of the simple string valued property like above. This is the closest thing to data types here. In the Qualified DC in RDF/XML document above, it is recommended to model like this (If I understand it correctly). <dc:subject> <rdf:Description> <rdf:value>19D10</rdf:value> <rdfs:label>Algebraic K-Theory of spaces</rdfs:label> <rdfs:isDefinedBy rdf:resource="URI2"/> </rdf:Description> </dc:subject> The rdfs:isDefinedBy might point to any relevant URI2 that defines the encoding - such as a term in a controlled vocabulary; this would not be to an RDF(s) document. Optionally an rdf:type might also be used to point to a node of type rdfs:Class in an rdf schema if such existed. The rdf:value isn't required to point to a literal; it might point to another blank node with another rdf:value, rdfs:label --- There is probably more, but I'll stop here. Dave
Received on Thursday, 7 February 2002 09:25:56 UTC