and closing connections most application programs will need only a limited set of tlpb functions if an application program is written directly to the tlpb the transport user function would be integrated into the application program transport user 18 may be logically linked to a protocol compensator 20 both the user and the protocol compensator where one exists will operate under the control of a control point 22 in node 10 protocol compensator 20 is tied to the communication system 26 through a transport protocol stack or transport provider 24 transport provider 24 defines the transport protocols that are actually implemented when data is exchanged between the two nodes over the communication system 26 examples of transport providers are layers 1 4 of osi or sna netbios tcp ip and others mentioned earlier one basic function of the protocol compensator 20 is to intercept tlpb verbs provided by the transport user and where appropriate to add information to the data stream to compensate for any mismatch between the protocol followed by a tlpb verb and the protocol followed by a corresponding verb or function in transport provider 24 another basic function is to accept data from the provider 24 and to modify the data stream to provide compensations needed to convert the data stream to tlpb representations more details as to the.