In the project "Hellenic Action for Multi-Media Information Systems and Applications" an onto centric ontological model was developed, which deals primarily with issues of representation of abstract semantic relations of historical context, space, time, incomplete and contradictory information. This model was implemented in the Semantic Indexing System (SIS). CLIO, a flexible cultural documentation system suitable for both movable objects and immovable monuments was based on this model. 
The CLIO knowledge representation model expresses a relatively general ontology, which can be supplemented with derived concepts specific to particular domains. This ontology includes concepts of matter, place, action, time, quantity, anthropological, intellectual creation and the relations between them.
Finally, the CLIO model is compatible with the international guidelines for the documentation of museum objects as defined in the information categories of the Documentation Committee of the International Council of Museums (CIDOC/ICOM). Furthermore, it has served as the basis for the recent proposal to the CIDOC/ICOM Data Models Working Group for an onto centric data model that will more fully serve the variety of documentation needs. 
Close collaboration with the Benaki Museum and the Historical Museum of Crete has been established for the analysis of the requirements of the CLIO. The CLIO system is used by the Documentation Department of Benaki Museum.