]> Top level classes for some of the major Open Biomedical Ontologies (OBO). Allows easy and succinct specification for OBO data types for SSWAP (http://sswap.info) RDGs (Resource Description Graphs). For example, to specify that a SSWAP semantic web service accepts Gene Ontology (GO) terms as input, the sswap:Subject node simply asserts that it is of rdf:type obo:GO. Use is analogous for specifying return data types with sswap:Object. See http://sswap.info for more information on SSWAP semantic web services.