Symbolic anatomic knowledge representation in the Read Codes version 3: structure and application.

The Read Thesaurus (Version 3 of the Read Codes) is a controlled medical vocabulary produced during the Clinical Terms Projects with the involvement of over 2,000 health care professionals from all United Kingdom specialties. In addition to allowing the transfer of clinical information in a meaningful way, it supports analysis of this information and provides a basis for the development of shareable medical knowledge bases. The thesaurus includes a comprehensive, dynamic set of over 7,000 gross anatomic concepts richly linked in a network with over 16,000 operative procedures and 40,000 disorders. The representation of anatomic concepts aims to balance the requirements for expressivity, clearness, and simplicity. The underlying directed acyclic graph hierarchy is independent of the alphanumeric code and enables continued refinement and expansion. A template table allows semantic definition, qualification, and linkage of concepts.