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

The formal URI for the code system. I.e. ValueSet.codeSystem.system (or its equivalent).

element_id	types
Extension
Extension.extension
Extension.url
Extension.value[x]	uri
Extension
Extension.id	http://hl7.org/fhirpath/System.String
Extension.extension	Extension
Extension.url	http://hl7.org/fhirpath/System.String
Extension.value[x]	uri