9.1.1 Support for the VoID and VANN vocabularies

The VoID aims at resolving the same problem as the Manifest files described here. In addition, the VANN vocabulary provides the information about preferred namespace prefixes. The RDF library manager can deal with VoID files. The following relations apply:

• VoID Dataset and Linkset are similar to lib:Ontology, but a VoID resource is always Virtual. I.e., the VoID URI itself never refers to an RDF document.

• The owl:imports and its lib specializations are replaced by void:subset (referring to another VoID dataset) and void:dataDump (referring to a concrete document).

• A description of the dataset is given using dcterms:description rather than rdfs:comment

• The RDF library recognises lib:source, lib:baseURI and lib:Cloudnode, which have no equivalent in VoID.

• The RDF library recognises vann:preferredNamespacePrefix and vann:preferredNamespaceUri as alternatives to its proprietary way for defining prefixes. The domain of these predicates is unclear. The library recognises them regardless of the domain. Note that the range of vann:preferredNamespaceUri is a literal. A disadvantage of that is that the Turtle prefix declaration cannot be reused.

Currently, the RDF metadata is not stored in the RDF database. It is processed by low-level primitives that do not perform RDFS reasoning. In particular, this means that rdfs:subPropertyOf and rdfs:subClassOf cannot be used to specialise the RDF meta vocabulary.