eHealth Infrastructure (v2019.5.3) 


<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>