Must Support

Conformance flag set in a StructureDefinition by an Implementation Guide.

Definition

mustSupport=true on an ElementDefinition means an implementation claiming to follow the profile must be able to provide the element when sending and process it without error when receiving. The exact meaning (populate, display, persist…) is not fixed by base FHIR: each Implementation Guide SHALL define it. Distinct from minimum cardinality 1..*, which is what actually makes an element mandatory.

Origin

Defined by HL7 FHIR (Profiling, the 'Must Support' section of ElementDefinition.mustSupport); semantics specified per IG, e.g. US Core — see hl7.org/fhir/profiling.html.

Example in context

<element><path value="Patient.identifier"/><min value="1"/><mustSupport value="true"/></element>

Related terms

• StructureDefinition — the resource that carries the flag.
• US Core IG — defines the operational semantics of mustSupport.