administrative view (i.e., represents the resource or service generally identified by the Access Identifier [AID] parameter). In the context of the ISO State Model, the term "entity" means "managed object". Different types of entities (such as hardware, transport facilities, and subscriber service) have a variety of state characteristics that express the availability of their underlying resources that are specific to each entity type. However, a state model is expected to be common to a large number of types of entities. It expresses key aspects of their availability at any given time. The purpose of the state model is to indicate the availability of an entity in providing its functions and, if an entity is not available, to indicate the cause of the unavailability and what kind of activity may be taken by the manager (e.g., the OS or the craft) to make the entity available. In a specific application, only a subset of the state model may be needed. The rationale of such restrictions is not described in GR-1093. The technology or application-specific requirements document should be consulted for this information. The standard definitions and mappings allow Operations Systems to gather state information from NEs and integrate it into a consistent representation of the status of the entire managed network and each of the services that it supports. To help ensure interoperability, particularly for an OS that interfaces with multiple NEs using one of the two state models, a mapping between the models may be needed. GR-1093 provides a mapping for the two models and also defines the extension to the OSI state/status attributes that is necessary to meet the telecommunications needs of the service providers. Telecommunications Management Network A concept of the network element as a distributed entity is widely used in TMN model which in turn is used as a standard for developing element management systems. See also Unbundled network element References Network management