Proposed policy, pending review by Vocabulary and HTA
- If the type of the element is "code":
- The value set SHOULD be defined as part of FHIR - exceptions require FMG approval. (FMG will consult with Vocab as appropriate)
- The binding strength SHALL be 'required'
- Codes SHOULD be mapped to v2 and/or v3 if equivalent concepts exist in those specifications
- If the type of the element is "Coding" or "CodeableConcept":
- For artifacts of FMM level 2 or lower, FHIR-defined codes are permitted to allow the implementer community to experiment and determine what terminologies are appropriate (if appropriate non-FHIR codes can't be found)
- For artifacts of FMM level 3 or higher, the value set SHALL NOT include codes defined as part of FHIR without FMG approval
- The codes should be drawn from V2, V3, CDA, or external code systems, e.g. as found on terminology.hl7.org
- The FMG will consult with HTA about any exceptions
- Shared value sets defined in terminology.hl7.org can be used if appropriate
- When binding to external terminologies, bindings cannot be stronger than "preferred" unless the terminology is free-for-use in the realm the specification is being published for. I.e. The whole world for UV specs and U.S. for us-realm specs. Note that a proprietary terminology such as SNOMED-CT MAY be referenced with "extensible" or "required" bindings for UV specs provided that the codes, designations and relationships needed to implement the specification are licensed by SNOMED International for free international use
- All value sets binding to external terminologies SHALL indicate or reference any licensing restrictions around the use of those terminologies.
- Mapping can be performed but is not required
- There are many legacy ValueSets for Coding/CodeableConcept that are defined in FHIR itself, in violation of the above rule. Replacing these with external content or gaining explicit approval for exceptions is an ongoing task. Priority will be given to those that are candidates for normative status.