Ontology and data representation as RDF (a) A part of the ontology for main entities represented as RDF graphs. C (pale blue rectangles) represents classes, P (pink rectangles) properties, A anonymous nodes, empty arrows rdfs:subClassOf, pink arrows rdfs:domain, green arrows rdfs:range, and red arrows owl:unionOf. (b) Relationship between data tables in a source database (Xperanto-TMA) and data graphs represented as RDF graphs. Name spaces are omitted for simplicity. Violet ellipses represent classes, orange rectangles object properties, green rectangles data type properties, and dotted arrows class-instance relationships.