The HL7 Version 3 Concept Descriptor (CD) Data Type includes a Qualifier component, which can "..constrain the meaning of the primary code, but cannot negate it or change it's meaning to that of another value in the primary coding system". The qualifier field is a list of Concept Role elements, which carry a name/CD tuple.
The HL7 CTS Specification includes supporting functions for both of these requirements:
- Note that these two methods don't define how equivalence and subsumption are determined - they simply define an interface that allows the question to be posed and an answer to be supplied
The CTS Specification, however, doesn't address compositional issues outside of the HL7 Messaging API space. Functions exist to determine whether two concept codes are related, and the code mapping API provides the ability to query the concept code in a target system that most closely approximates the source target, but again it only addresses a single concept code.