A grouping of SDL user data whose boundaries are preserved from one end of the signalling data link connection to the other.
Data transfer
The phase in connection and connectionless modes that supports the transfer of data between to signalling data link users.
SDL provider
The signalling data link layer protocol that provides the services of the signalling data link interface.
SDL user
The user-level application or user-level or kernel-level protocol that accesses the services of the signalling data link layer.
Local management
The phase in connection and connectionless modes in which a SDL user initializes a stream and attaches a PPA address to the stream. Primitives in this phase generate local operations only.
PPA
The point at which a system attaches itself to a physical communications medium.
PPA identifier
An identifier of a particular physical medium over which communication transpires.
