Resource Description Framework
Core data model for the Semantic Web. Subject-predicate-object triples. Foundation of all semantic web technologies.
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Where this one tends to earn its keep.
Foundation for all knowledge graph data models
Linked data publishing and consumption
Metadata interchange standard
Graph database data representation
I haven't checked this label against the actual licence text — it's the catalogue's original guess. Check the ontology's own site before you rely on it.
Others worth a look in Web Standards.