VTAM® supervises telecommunications activity in a Systems Network Architecture (SNA) network. VTAM helps direct data transfer between application programs and devices, such as terminals, and between different application programs.

This manual discusses data-transfer application programs that conform to the rules of LU type 6.2 protocols, also known as advanced program-to-program communication (APPC) protocols. LU 6.2 protocols and services are defined by SNA to support communication between type 6.2 logical units. (For a definition of logical units, see Logical units.)