<ProcedureRequest xmlns="http://hl7.org/fhir"> <id value="ehealth-procedurerequest-genexample"/> <requisition> <system value="http://www.acme.com/identifiers/patient or urn:ietf:rfc:3986 if the Identifier.value itself is a full uri"/> <value value="123456"/> </requisition> </ProcedureRequest>