My only thought is that it seems a bit like a hack and may be too restrictive when trying to categorise classes. Ie it looks like you intend to have ALL RDF classes under the namespace http://rs.tdwg.org/ontology/ (correct me if I am wrong). This will result in a huge list of classes at the one level, and hence, again diminishing the human readability of the ontology. I wouldnt know, but it sounds like it also might cause ontology management headaches later on? Kevin

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Roger Hyam <roger@tdwg.org> 09/26/06 8:49 PM >>>

Hi Everyone, In the not very comforting words of software vendors these are "known issues" and will be resolved in the next release ;) But seriously.The namespaces in the TCS names vocabulary do not resolve because we didn't have a policy at that time. The use if entity references was 'borrowed' from an example (probably Protege output) and I wouldn't mind doing away with it. I have been thinking long and hard about the namespace issues in the last few weeks and believe I have a solution that I will propose at TDWG St Louis. It would be good to have face to face discussions about it and make a decision there. To briefly summarize: The issue is getting a namespace convention that will work across technologies. Suppose we want to serve data in a technology that "isn't very good at namespaces". As an example - if we were to have separate namespaces for TaxonNames, TaxonConcepts, Specimens, Metadata, GeospatialStuff, Collections and we wanted to validate a document using XML Schema that contained all these things it would require 6 independent schemas each with it's own target namespace. If you have ever tried to debug something like this you will know what total madness it is. We can't just abandon XML Schema because it would rule out not only our existing technologies but GML and probably others... It may also be desirable to express our ontology in things that aren't even XML. The only solution I can think is that for the TDWG Ontology we should have a single formal namespace of: http://rs.tdwg.org/ontology/ Within the ontology we have a convention for concepts that goes like this. A class would be: http://rs.tdwg.org/ontology/tdwg123_MyClass where 123 is the internal id of the class and MyClass is the class name A property in MyClass would be: http://rs.tdwg.org/ontology/tdwg123_myProperty where 123 is the *class* id not the property id and myProperty is the property name. An instance would be http://rs.tdwg.org/ontology/tdwg123_789 where 123 is the *class* id and 789 is the instance id (there is nothing stable about an instance that we could use as an identifier unless we force a label property and make it immutable). In a way this is using the part before the _ as a pseudo namespace. I think this hits the balance between something that is technology independent and something that will produce reasonably human readable documents. It is radical which is why I thought it would be good to talk about it. Any one got an alternative? We have to have a solution for this by the end of the St Louis meeting as it is critical path for ontology work. Most grateful for you patience and any thoughts you have. Roger Sally Hinchcliffe wrote:

Hi Steve /all

We took that syntax straight from Roger's RDF/TCS examples. I think Roger was going to do more work on tidying up those sorts of loose ends. I have to admit that my knowledge of RDF and particularly RDFS is pretty superficial

We can switch to either the shorter format or the safer fully qualified URI - what do people think would be better?

Sally

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By the way, the IPNI example you cite has an error:

<tn:nomenclaturalCode rdf:resource="&tn;#botanical" />

Many RDF/XML parsers will see &tn; as an entity which cannot be resolved. Since I don't have a copy of the ontology (and http://tdwg.org/2006/03/12/TaxonNames does not resolve), I can only take a guess that it should look something like:

<tn:nomenclaturalCode rdf:resource="tn:botanical" />

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

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fully qualified resource URI which looks like:

<tn:nomenclaturalCode rdf:resource="http://tdwg.org/2006/03/12/TaxonNames/botanical" />

-Steve

*** Sally Hinchcliffe *** Computer section, Royal Botanic Gardens, Kew *** tel: +44 (0)20 8332 5708 *** S.Hinchcliffe@rbgkew.org.uk

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