An economical solution is to work in a federated environment, where specialist thesauri are mapped to a small set of well-defined, generic concepts used to browse for documents, objects, publications, etc. of interest. In such an implementation, specialist thesauri retain their autonomy and continue to be managed independently, thus the cost of maintaining the mappings is smaller. Furthermore, mappings from specialist thesauri to this mediating structure permits end-users to query multiple resources at once, using the same terms as always.
The following picture represents the BackBone Thesaurus (BBT) federated thesauri service:
Figure: The BackBone Thesaurus Federation
