Current Version - Under Revision
Standard message specifications and communication agreements with particular user communities often specify restricted lists of codes that can be used in particular message elements:
- Examples of this include the HL7 idea of "vocabulary domains" containing " value sets " specified for use either in a general or specific context in a message element;
- The UK NHS specification for laboratory report messages, which refers to a "bounded list" of Read Codes that are to be used in particular fields of the message.
It is inevitable that a broad terminology such as SNOMED CT needs to be restricted in this way. A message element intended for representation of a |requested radiology investigation| must clearly contain a Concept Identifier that represents a radiology procedure. The limitations may go further than this. The list of procedures that can be requested may be restricted by local convention or regulation.
A Concept Reference Set can be used to represent value sets that are permitted in a particular type of message or within a particular user community. This facilitates use of a general-purpose SNOMED CT enabled Terminology services to populate and validate the coded elements of messages.