Admitted patient service units should be differentiated by target population and program type. For example, if a hospital had separate wards for child and adolescent and general adult populations, these should be reported as separate service units. Similarly, if the hospital provided separate wards for older persons acute and older persons other program types, such as rehabilitation or extended care, this would require separate service units to be identified (that is, defined by the Specialised mental health service—admitted patient care program type, code N data element as well as the Specialised mental health service—target population group, code N data element). Where a hospital has, for example, two older persons acute admitted patient service units, these only need to be reported as one combined older persons acute admitted patient service unit to satisfy the minimum reporting requirements for NMDS purposes, but could be reported as two separate service units if desired. For additional information, please refer to the glossary item Admitted patient mental health care service.The complete identifier string, including State/Territory identifier, Region identifier, Organisation identifier, Hospital identifier and Admitted patient service unit identifier, should be a unique code for the service unit in that state/territory. Where applicable, service unit reporting structures should be identical between all mental health collections (e.g., Mental Health National Minimum Data Sets and the Mental Health National Outcomes and Casemix Collection (NOCC)).