Conformance requirements on $expand

[jmandel]

https://build.fhir.org/ig/HL7/US-Core-R4/clinical-notes-guidance.html#using-expand isn't linked to from the profiles, and it's unclear whether servers are required to support $expand. (And if so, on all context values, or just on a few specific ones?)

Without $expand, a client has no way to query for all DiagnosticReport resources, since GET /DiagnosticReport?patient=[] is not defined (the only query requires a patient and a code, and a client has no way to know/guess all possible codes that a server might be using, without $expand). Even with $expand it's not clear whether this operation would be required to return all codes used across all DiagnosticReports available across all Patient records, or just a kind of "preferred" list (in which case, again clients would have no way to locate all DiagnosticReports).

[brettmarquard]

Will add SHOULD support to DocumentReference and DiagnosticReport

[Healthedata1]

added SHOULD Support to ValueSet in capstatement. Need to review to see if needs to be more specific. i.e. add in context this is limited to.

[Healthedata1]

discuss on 9/11 Argo R4 call: proposal GF#24089 to add query by patient