Figure 1 graphically describes the rule-based mediation methodology. Information from one or more data sources sharing the same data format is loaded into that format's syntactic ontology. Each syntactic ontology is linked to the common core ontology using a set of rules called a description. The rules are composed of linked mappings and filters on those mappings. Once data has been integrated into the core ontology, it can be queried, and the response formatted according to whichever syntactic ontology the user wishes.