[tdwg-tag] literal enumerated values in TCS-RDF

Steve Perry smperry at ku.edu
Tue Oct 3 05:32:49 CEST 2006

I agree with Rod and Gregor that we ought to use full URIs to indicate 
nomenclatural codes.

Gregor is right that we could use


as an abbreviated reference to such a URI, so long as we provide an 
entity definition for tn in an embedded DTD.  If this is done properly, 
RDF parsers can handle it (because the entity is expanded during XML 
parsing).  However, it's easy to lose the DTD when copying and pasting, 
when creating your own RDF using someone else's as an example, or when 
using text processing routines on serialized RDF/XML.

DTDs are defined at the document level while non-anonymous/non-blank RDF 
resources are global and the full description of a global resource can 
be split among multiple files.  To cut down the likelihood of errors we 
should probably keep it simple and suggest the use of full URIs as a 
best practice.


Gregor Hagedorn wrote:
> Steve writes:
>>>>> However, using XML namespace prefixes in resource references inside
>>>>> RDF/XML documents tends to cause problems because not all RDF/XML
>>>>> parsers are smart enough to dereference the namespace prefix and  
>>>>> build a fully-qualified resource URI.  A safer form of the above would be  
>>>>> the fully qualified resource URI which looks like:
>>>>> <tn:nomenclaturalCode  
>>>>> rdf:resource="http://tdwg.org/2006/03/12/TaxonNames/botanical" />
> It seems the discussion confuses QNames ("namespace-colon") and XML-Entities 
> (ampersand-semicolon) - or am I confused???
> An attempt to clarify: From my understanding, xml itself has no such thing as a 
> namespace-colon in literals - xml-schema has introduced it as a convenient 
> thing (QName). However, the use of xml-entities is a requirement of xml 1.0 
> itself. I agree with Rod that URIs are correct way for RDF:
>   rdf:resource="http://tdwg.org/2006/03/12/TaxonNames/botanical"
> and under no circumstances (even with RDF-xml-Schema) can we use
>   rdf:resource="tn:/botanical"
> because RDF does not use QNames. However, we can use (if abbreviation is an 
> issue, and providing an entity definition for it, as the protege examples do.)
>   rdf:resource="&tn;/botanical"
> If RDF-parsers fail to deal with the latter, they are grossly non-interoperable 
> with xml as a whole.
> Gregor----------------------------------------------------------
> Gregor Hagedorn (G.Hagedorn at bba.de)
> Institute for Plant Virology, Microbiology, and Biosafety
> Federal Research Center for Agriculture and Forestry (BBA)
> Königin-Luise-Str. 19           Tel: +49-30-8304-2220
> 14195 Berlin, Germany           Fax: +49-30-8304-2203
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