The purpose of ontologies (sets of knowledge-bearing assertion types), taxonomies (classes of things, ideas, etc.), and vocabularies (such as markup vocabularies) is to allow the human members of communities of interest to communicate among themselves about the things with which their communities are concerned.

However, knowledge that is represented in the terms of a specific community may have high value outside its community of origin. How can distinct bodies of knowledge, created and maintained by distinct, non-cooperating communities, be made usefully available in contexts other than their communities of origin? One answer is to merge them with other bodies of knowledge, in conformance with the Reference Model of ISO 13250 Topic Maps.