Federated identity platform on the basis of digital content require sophisticated descriptions of that content, as well as service-oriented carrier architectures that allow negotiating and enforcing contract and license schemes in heterogeneous digital application environments. So this paper gives ontology in the Web Ontology Language (OWL) for federated identity systems, giving explicit, formal, and general specifications of a conceptualization of such architecture. OWL ontologies are standardized, machine-readable formats that support automated processing with Semantic Web applications. Intermediate concepts, concepts between base-level concepts and higher level concepts, are central in a federated identity system.