Timbr allows creating virtual PKs for concepts (used as unique identifiers), and FK to PKs in the ontology (used as relationships between concepts). As long as the ontology author maps the physical tables PKs to the ontology PKs, client join will follow these declarations. In the ontology, you can create relationships between concepts using FK statements. In each relationship, you specify the properties in the ontology that represent the relationship (used for the JOIN).
