http://hl7.org/fhir/StructureDefinition/valueset-reference|4.0.1

A logical reference (e.g. a reference to ValueSet.url) that identifies the value set/version that identifies the set of possible coded values this coding was chosen from or constrained by.
element_idtypes
Extension
Extension.extension
Extension.url
Extension.value[x]
Extension
Extension.id
Extension.extension
Extension.url
Extension.value[x]