<status value="retired"/> <date value="2014-03-26"/> <description value="Observation values used to assert various populations that a subject falls into."/> <compose> <include> <system value="http://terminology.hl7.org/CodeSystem/v3-ObservationValue"/> <filter> <property value="concept"/> <op value="is-a"/> <value value="_ObservationPopulationInclusion"/> </filter> </include> </compose> </ValueSet>