OMG/HL7 CTS2 Standard

The Object Management Group's Common Terminology Services Version 2 (CTS2) standard defines an accepted industry standard service interface to share, query and maintain value sets and other terminology artifacts. In a nutshell, it is based on a Service Functional Model (SFM) developed by the HL7 community. This specification facilitates the definition of designations and mutual relations of concepts with a common interface. The interface captures the behavioral aspects and requirements of the terminology services and relies on static information models. In this way, controlled vocabularies are accessible and manageable.

The main artefacts of CTS2 are

• code systems (and its versions), defined by an “authority”, e.g. by HL7 or even by a small project,
• entities, i.e. concepts, as elements of code systems with an unique code, together with its designations and associations (e.g. is a) between them,
• value sets, i.e. sets of entities, which serve as domains for coded attributes, and
• mappings between code systems.

The CTS2 specification is structured within a platform independent model that provides two profiles: (1) Structural profiles define how code systems, associations, or value sets are organized; (2) Functional profiles define fundamental operations of persistent storage (CRUD) in an information system that change these structures. In addition, the platform independent model is accompanied by a platform specific model that includes implementation profiles for the web service protocol SOAP and for simple HTTP calls via Representational State Transfer (REST) .