- From: Bernard Vatant <bernard.vatant@mondeca.com>
- Date: Wed, 16 Mar 2011 23:17:02 +0100
- To: Thomas Baker <tbaker@tbaker.de>
- Cc: Alistair Miles <alimanfoo@googlemail.com>, Simon Reinhardt <simon.reinhardt@koeln.de>, Bob DuCharme <bob@snee.com>, SKOS <public-esw-thes@w3.org>, Pierre-Yves Vandenbussche <pierre-yves.vandenbussche@mondeca.com>
- Message-ID: <AANLkTi=P0Hg7uDTk4OX+vb8cZP=DPQEYE0CzfyjMgTyR@mail.gmail.com>
Hello all For what is worth, among the 85 "linked open vocabularies" we have started to gather at [1], more than a half (46) use dc: namespace for their metadata, and 47 rely on dcterms: (for metadata, or otherwise). And singularly dc:title seems to keep a great popularity among RDF vocabularies creators :) BTW stay tuned at [1], for which new interface features are currently polished at Mondeca Labs and should be announced soon. [1] http://labs.mondeca.com/dataset/lov 2011/3/16 Thomas Baker <tbaker@tbaker.de> > On Wed, Mar 16, 2011 at 11:18:45AM +0000, Alistair Miles wrote: > > > Doesn't answer your question, but: > > > The DC terms namespace contains all the elements properties, so > http://purl.org/dc/terms/title exists: > > > http://dublincore.org/documents/dcmi-terms/#terms-title > > > > AFAIK all the properties from the dc elements namespace have been > "copied" > > into the dc terms namespace. I believe the main reason for doing this was > > to allow domains and ranges to be defined on the properties in the dc > terms > > namespace. E.g., dcterms:title has range rdfs:Literal, and dcterms:author > has > > range dcterms:Actor. I think the hope was to support more consistent > usage of > > properties like dcterms:author (usage of > http://purl.org/dc/elements/1.1/author > > is highly variable, and many people will put literals in the object > position). > > > > So if you're doing RDF, the http://purl.org/dc/elements/1.1/ namespace > is > > effectively deprecated, use http://purl.org/dc/terms/ instead. If you > want > > to know more, Tom Baker is the man to ask. > > Thank you for the good summary, Alistair! > (Note: s/author/creator/, s/Actor/Agent/) > > 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> > > -- Bernard Vatant Senior Consultant Vocabulary & Data Engineering Tel: +33 (0) 971 488 459 Mail: bernard.vatant@mondeca.com ---------------------------------------------------- Mondeca 3, cité Nollez 75018 Paris France Web: http://www.mondeca.com Blog: http://mondeca.wordpress.com ----------------------------------------------------
Received on Wednesday, 16 March 2011 22:17:35 UTC