> From: Dublin Core Social Tagging 
> [mailto:[log in to unmask]] On Behalf Of Liddy Nevile
> Sent: 02 November, 2006 16:51
> To: [log in to unmask]
> Subject: Re: [DC-SOCIAL-TAGGING] The "social" in social 
> tagging (Was RE: Welcome!)
> 
> what would happen if you had "dctag:subject=UTube funk music 
> soul" so that the definition of dctag was closely related to 
> but not purporting to be dc:subject?  (I am assuming dctag 
> was defined in a
> namespace.)

It's not clear to me why you would want to invent a new namespace
for the definition of dctag when it was related to but not
purporting to be dc:subject.  This seems similar to what is done 
with encoding schemes, e.g., dct:DDC, dct:LCC, dct:LCSH, dct:MESH, 
dct:NLM, dct:TGN and dct:UDC.  Taken from "Expressing Qualified 
Dublin Core in RDF /XML" document:

 <dc:subject>
   <dcterms:MESH>
     <rdf:value>D08.586.682.075.400</rdf:value>
     <rdfs:label>Formate Dehydrogenase</rdfs:label>
   </dcterms:MESH>
 </dc:subject>

It seems like you could just define a new encoding scheme, e.g.,
dcterm:TAG, to handle the semantics of social tagging.  However,
that might not be enough.  Organizations such as Flickr, YouTube, 
etc. may desire slightly different semantics for their social
tagging.  DCMI probably doesn't want to keep defining new encoding
schemes on a regular basis.

However, DCMI would not need to define new encoding schemes on a 
regular basis since the above qualified Dublin Core really boils
down to:

 <dc:subject>
   <rdf:Description>
     <rdf:type rdf:resource="http://purl.org/dc/terms/MESH"/>
     <rdf:value>D08.586.682.075.400</rdf:value>
     <rdfs:label>Formate Dehydrogenase</rdfs:label>
   </rdf:Description>
 </dc:subject>

Which generates the same exact RDF triples.  This implies that 
anybody can create new encoding schemes and semantics, albeit 
not in the dcterms: namespace since it is controlled by DCMI, 
and still be compatible with the DCMI model.  So if Flickr
wanted to define their definition of tags they could just do:

 <dc:subject>
   <rdf:Description>
     <rdf:type rdf:resource="http://www.flickr.com/photos/tags/"/>
     <rdf:value>D08.586.682.075.400</rdf:value>
     <rdfs:label>Formate Dehydrogenase</rdfs:label>
   </rdf:Description>
 </dc:subject>

Which would provide interoperability with Dublin Core without DCMI
lifting a finger.  Internally at OCLC, for research projects, we 
have been using this interoperability practice for defining new 
encoding schemes to controlled vocabularies that DCMI has not defined.
For example, GSAFD, NGL, RVM, etc.


Andy.