- From: Ron Daniel <rdaniel@interwoven.com>
- Date: Fri, 29 Jun 2001 09:12:24 -0700
- To: "RDF Core" <w3c-rdfcore-wg@w3.org>
Hi all, I had an action to bring up another point about rdf:ID and rdf:about. The idea of an isDefinedBy predicate has been mentioned. While that would be an extension of the 1.0 M&S, and thus out of scope for the clarification document, if we combine rdf:ID and rdf:about now, we won't be able to add such a thing later. Is it important to add such a thing? Don't know, but I do know of at least one situation where I've made use of the distinction the M&S 1.0 spec makes between the two. PRISM is a metadata specification that makes extensive use of terms in controlled vocabularies. For example, to indicate that a story is about Greece, the PRISM description of that story would contain: <rdf:Description rdf:about="story.txt"> <dc:coverage rdf:resource= "http://prismstandard.org/vocabs/ISO3166/GR" /> [...] Unless the system receiving such a description already knows about the ISO3166 vocabulary, it can't do anything that is human meaningful with that. Since PRISM expects there to be many controlled vocabularies used, we can't assume that the receiver will know all of them. So, PRISM shows a particular RDF idiom: <dc:coverage> <pcv:Descriptor rdf:about= "http://prismstandard.org/vocabs/ISO3166/GR"> <pcv:label xml:lang="en">Greece</pcv:label> <pcv:label xml:lang="fr">Grece</pcv:label> </pcv:Descriptor> </dc:coverage> which allows some information (in this case, the human readable label) about the controlled vocabulary entry to be provided in-line. Sort of like pre-filling a cache. Systems just have to know how to handle the pcv:label predicate, i.e. 'show this to the user', a much smaller task than having to know all possible vocabularies. So note that the rdf:about attribute was used above. This was to explicitly indicate that the in-line description was NOT the authoritative description of the GR resource. The PRISM spec says that when you do create a document that IS the authoritative definition of that resource, the rdf:ID attribute must be used instead. So, this is one data point where the difference between the two was used, based on what the M&S 1.0 spec says. Presumably, in the future the implementations could be updated to insert an isDefinedBy predicate if such a thing were created. However, having provided that data point, I want to point out that the question we need to address is whether such a difference is valuable enough to be maintained. PRISM's world would not collapse if that difference were erased. Also, it would avoid the ugly situation where multiple graphs claim to be the authoritative definition for a resource. Regards, Ron Daniel Jr. Standards Architect Tel: +1 415 778 3113 Fax: +1 415 778 3131 Email: rdaniel@interwoven.com Visit www.interwoven.com Moving Business to the Web
Received on Friday, 29 June 2001 12:14:11 UTC