- From: Alistair Miles <alimanfoo@googlemail.com>
- Date: Fri, 18 Mar 2011 12:14:22 +0000
- To: Thomas Baker <tbaker@tbaker.de>
- Cc: SKOS <public-esw-thes@w3.org>
On Wed, Mar 16, 2011 at 05:31:00PM -0400, Thomas Baker wrote: > (Note: s/author/creator/, s/Actor/Agent/) Sorry!!! Me randomly inventing new stuff in the dc namespaces is the last thing you needed :) Someone should write a namespace validator for my emails :) Cheers, Alistair > > This question will be at the top of a revamped FAQ, as it keeps > coming up, and in many contexts. Two years ago on this very list, > I wrote [1]: > > DCMI has gotten alot of positive feedback from the Semantic Web > community on the "makeover" of DCMI properties with domains and > ranges. A longer explanation, with historical context: > > dc:title [1] and dc:subject [2] (and the other thirteen Dublin > Core properties) were among the first RDF properties declared > anywhere. They were declared as RDF properties before W3C > standardized the notion of "range" in the RDF Schema > specification. > > As RDF matured, the DC properties became criticized in SW > circles for being underspecified. DCMI wanted to assign ranges, > but in doing so did not want to "break" existing legacy data, > which used "subject" (for example) both with literal and > non-literal values. > > As described in [4, paragraphs starting "Formal domains..."], > DCMI resolved this dilemma by creating fifteen properties in the > /terms/ namespace in parallel to the corresponding terms in the > /elements/1.1/ namespace, and declared the former as > subproperties of the latter. > > It is not actually incorrect to continue using dc:subject and > dc:title -- alot of Semantic Web data still does -- and since > the range of those properties is unspecified, it is not actually > incorrect to use (for example) dc:subject with a _literal_ value > or dc:title with a _non-literal_ value. However, good Semantic > Web practice is to use properties consistently in accordance > with formal ranges, so implementers are encouraged to use the > more precisely defined dcterms: properties. > > Tom (wearing his DCMI hat) > > [1] http://dublincore.org/documents/dcmi-terms/#elements-title > [2] http://dublincore.org/documents/dcmi-terms/#elements-subject > [3] http://dublincore.org/documents/dcmi-terms/#H1 > [4] http://dublincore.org/documents/dcmi-terms/#terms-subject > [5] http://lists.w3.org/Archives/Public/public-swd-wg/2009Jan/0000.html > > Tom > > [1] http://lists.w3.org/Archives/Public/public-esw-thes/2009Jun/0017.html > > -- > Tom Baker <tbaker@tbaker.de> -- Alistair Miles Head of Epidemiological Informatics Centre for Genomics and Global Health <http://cggh.org> The Wellcome Trust Centre for Human Genetics Roosevelt Drive Oxford OX3 7BN United Kingdom Web: http://purl.org/net/aliman Email: alimanfoo@gmail.com Tel: +44 (0)1865 287669
Received on Friday, 18 March 2011 12:15:01 UTC