8. A repository system, including: a metadata repository storing metadata including records defining taxonomies and records using the taxonomies to define taxonomy values, the metadata repository having a service interface exposing a data update service for updating the data in records and also exposing a taxonomy search service; and a taxonomy editor arranged as a client of the metadata repository, arranged to call the data update service to edit the definitions of taxonomies and to edit the taxonomy values stored in records; wherein the taxonomy editor is arranged to send a message to the taxonomy search service for at least one called taxonomy to cause the taxonomy search service to search the metadata repository for inconsistency between the at least one called taxonomy and the metadata stored in the repository, the message indicating the at least one called taxonomy; wherein the taxonomy search service is arranged to send a reply message, the reply message indicative of the inconsistency between the at least one called taxonomy and the metadata stored in the repository.
9. A repository system according to claim 8 wherein the taxonomy search service is arranged to return the identity of records having a data type incompatible with the at least one called taxonomy.