We thought about introducing the following two elements which will enable us to refer to attributes inside an XML element. Building on that we can then define annotations for attributes.
<model> <listOfCompartments> <compartment metaid=”c1” name=”cell” size=”3” /> <annotation> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <rdf:Description rdf:about="#c1"> <bqbiol:is> <rdf:Bag> <rdf:li rdf:resource="urn:miriam:obo.go:GO%3A0031594"/> </rdf:Bag> </bqbiol:is> </rdf:Description> <rdf:Description rdf:about="#c1.size"> <bqbiol:isDescribedBy> <rdf:Bag> <rdf:li rdf:resource="urn:miriam:pubmed:12343565"/> </rdf:Bag> </bqbiol:isDescribedBy> </rdf:Description> </rdf:RDF> </annotation> </compartment> </listOfCompartments> </model>
It may be that we don't need to, in practice, annotate the attribute itself rather than the attribute value. We don't anticipate that there will be a situation where the attribute and value will be annotated separately, so the same annotation style can be used for both.
We also discussed using XPath (//[@metaid='c1']/@size) to reference attributes, but it was decided that XPath wasn't necessary, and it was simpler to just use the extension of the current way of referencing an element metaid within the RDF.