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eProcurement Ontology (ePO)

European Union · OWL/RDF ontology of procurement semantics SIGNET support: Normative mapping — the semantic layer

What it is

The EU eProcurement Ontology is a formal OWL/RDF ontology defining the concepts and relationships of public procurement — buyers, tenderers, procedures, awards, and the properties connecting them. It gives European procurement data a shared machine-readable semantics, so that data published by different systems can be linked and reasoned over consistently.

The ontology is maintained by the Publications Office of the European Union. Official reference →

How SIGNET supports it

ePO sits in SIGNET's normative mapping tier, with a distinctive role: rather than mapping a single object, it aligns the semantics of the whole model. SIGNET's canonical serialisation is JSON-LD, and the JSON-LD context maps SIGNET terms to their ePO equivalents where they exist — procuringParty to ePO:hasBuyer, submittingParty to ePO:hasTenderer, Party to the ePO Agent, and so on across the vocabulary.

The consequence is that every SIGNET document is simultaneously ordinary JSON to a conventional consumer and linked data to a semantic one. A regulator or researcher can load SIGNET data into an RDF triple store and query it in ePO terms without any transformation step, because the alignment travels inside the document rather than living in an external crosswalk that can drift.

This is the linked-data design principle made operational: every object and property has a global URI, and where Europe has already defined the meaning of a procurement concept, SIGNET points at that definition rather than minting a rival one.

Where it lives in the standard