SPARQL Protocol and RDF Query Language
Query language for RDF databases. Retrieval and manipulation of knowledge graph data via endpoints.
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Where this one tends to earn its keep.
Query knowledge graphs and linked data endpoints
Federated queries across distributed RDF stores
Data integration via SPARQL endpoints
Build semantic search applications
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.