General Formal Ontology (GFO)

see: http://www.onto-med.de/ontologies/gfo/

The General Formal Ontology is a top-level ontology for conceptual modeling, which is being constantly further developed by Onto-Med. It includes elaborations of categories like objects, processes, time and space, properties, relations, roles, functions, facts, and situations. Moreover, we are working on an integration with the notion of levels of reality in order to more appropriately capture entities in the material, mental, and social areas. Outstanding features of GFO are:

• coherent integration of objects and processes (based on a novel category of persistants)
• time and space entities as entities sui generis, and the relation of coincidence
• a category of situoids, comprehensible wholes of the most independent character
• elaborate accounts of functions and roles
• openness regarding philosophical positions such as realism, conceptualism, or nominalism by the provision of different kinds of categories as universals, concepts, or symbolic structures

Ref. also: http://en.wikipedia.org/wiki/General_formal_ontology