Canonical IRIs from the OWL 2 vocabulary. See https://www.w3.org/TR/owl2-overview/.
owl:Ontology.
owl:Class.
owl:ObjectProperty.
owl:DatatypeProperty.
owl:Thing (the top class in OWL).
owl:Nothing (the bottom class — always empty).
owl:imports.
owl:sameAs.
owl:equivalentClass.
owl:equivalentProperty.
owl:inverseOf.
The OWL namespace IRI:
http://www.w3.org/2002/07/owl#.