Behavior when parameters are not specified (defaults) and/or when there are no descriptions meeting criteria (fall back) should be specified.
- For the $expand operation we need to be able to specify one or more "Context of Use" which would allow us to specify such, and in a SNOMED CT context this would be a language reference set. Are we adjusting the display element in these cases? This will be irrespective of language ie include that designation regardless of the language specific or featured in that description.
- In the designation as part of the response, we want to specify an array of "contexts of use" for each term, which specifies if the term is acceptable, preferred or ?unacceptable for that context. ML: We would only return designation that match the given language reference sets and allow the client to decide the order of preference.
- Do we want to specify Preferred or Acceptable in the request? Or can we assume Preferred. ML Suggested that we'd return all and let the client decide which it wants.
Further questions - when filtering do we need to indicate the language used in the search criteria such that only terms in that language should be matched against it?
Defaults and fallbacks - if there are no terms found matching the specified context of use then we have the option of returning some (server decides) fallback term and indicating "unacceptable"
Note that we can already return designations in languages that differ from that of the ValueSet itself using ValueSet.compose.include.concept.designation.language
TODO Define a StructureDefinition to describe proposed solution.