This is the first of a series of blog posts on the Open Citations blog that address the problem of citing data entities, for example a data package in a data repository, rather than bibliographic entities such as journal articles. For these purposes, the existence of DataCite to assign DOIs to datasets, and extensions to the SPAR (Semantic Publishing and Referencing) Ontologies to handle data items, are both important. This post addresses the second of these two issues.
As described in the previous blog post, CiTO, the Citation Typing Ontology, focuses on providing ontological properties to characterize citations of bibliographic entities. However, several of its relationships can also be used in relation to data entities:
Sub-classes of cito:cites
When attempting to map the DataCite metadata elements to ontology terms, to be described in a subsequent blog post, we encountered the DataCite requirement for the properties compiles and isCompiledBy, which are absent from CiTO and other ontologies that we know about and which cannot be conceived as relating to bibliographic entities.
Conscious of a growing need to specify metadata for data entities as well as bibliographic entities, and reluctant to include in CiTO relationships that cannot be applied to bibliographic entities, Silvio Peroni and I have thus created CiTO4Data, a new ontology within the SPAR ontology suite, to be found at http://purl.org/spar/cito4data/.
CiTO4Data, the Citation Typing Ontology for Data, is an extension ontology written in OWL 2 DL that imports CiTO, the Citation Typing Ontology, and adds extra object properties that are relevant only for datasets, computer programs and other similar digital objects, but not for conventional bibliographic entities.
To date, CiTO4Data adds just a single new object property
and its inverse
created to meet the need of encoding the DataCite Metadata Kernel v2.0 into RDF. We intend to expand CiTO4Data to include other properties relevant only for citing data entities, as the need arises.
NOTE: In the summer of 2012, we decided for simplicity to include these two properties within CiTO itself (as cito:compiles and cito:isCompiledBy), and to deprecate the CiTO4Data ontology.