specific application service element (OSI) (SASE)
The special application service elements are called Specific Application Service Elements(SASE) and contain special application-specific services.
The best known include File Transfer Access and Management( FTAM), Job Transfer and Manipulation( JTM), Virtual Terminal( VT), Message Handling System according to X.400, Manufacturing Message Specification( MMS) and Directory Service( DS) according to X.500.