OIL (Ontology Inference Layer or Ontology Interchange Language) can be regarded as an ontology infrastructure for the Semantic Web. [1] OIL is based on concepts developed in Description Logic (DL) and frame-based systems and is compatible with RDFS.
OIL was developed by Dieter Fensel, Frank van Harmelen ( Vrije Universiteit, Amsterdam) and Ian Horrocks ( University of Manchester) as part of the IST OntoKnowledge project.
Much of the work in OIL was subsequently incorporated into DAML+OIL and the Web Ontology Language (OWL).