In the IBM Systems Network Architecture (SNA), Logical Unit (LU) 6.2. See also LU.
(Advanced Program-to-Program Communications) A high-level protocol from IBM that allows one program to interact with another across the network. It supports client/server and distributed computing by providing a common programming interface on all IBM platforms. APPC provides commands for managing a session, sending/receiving data and transaction security and integrity (see two-phase commit). APPC commands have differed across platforms; however, the CPI-C interface defined a standard set of verbs (see CPI-C). APPC and LU 6.2 APPC software is either part of, or optionally available, on all IBM and many non-IBM operating systems. Since APPC has only supported SNA, which utilizes the LU 6.2 protocol for session establishment, APPC and LU 6.2 have been considered synonymous.