Maintenance activities can be classified into different categories. This specification uses the mechanism of the ConditionClassIddefined for conditions in OPC 10000-9, for such a classification of maintenance activities. In the following, specific subtypes of MaintenanceConditionClassTypeare defined, that should be used as ConditionClassIdfor specific maintenance activities. Other companion specifications and vendors might add additional subtypes of MaintenanceConditionClassTypeand might inherit from the types defined in this specification.