A management domain typically contains a large amount of management information. Each individual item of（  ）information is an instance of a managed object type. The definition of a related set of managed （  ）types is contained in a Management Information Base (MIB)module. Many such MIB modules are defined. For each managed object type it describes， a MIB （  ） defines not only the semantics and syntax of that managed object type， but also the method of identifying an individual instance so that multiple （  ） of the same managed object type can be distinguished. Typically， there are many instances of each managed object （  ） within a management domain。