<status value="active"/> <experimental value="false"/> <date value="2014-03-26"/> <description value="Definition: A factor, such as a microorganism, chemical substance, or form of radiation, whose presence, excessive presence, or (in deficiency diseases) relative absence is essential, in whole or in part, for the occurrence of a condition. Constraint: The use of this participation is limited to observations."/> <immutable value="true"/> <compose> <include> <system value="http://terminology.hl7.org/CodeSystem/v3-ParticipationType"/> <filter> <property value="concept"/> <op value="is-a"/> <value value="CAGNT"/> </filter> </include> </compose> </ValueSet>