(ACF/NCP, usually called just "NCP") The primary SNA network control program, one of the ACF products. ACF/NCP resides in the communications controller and interfaces with ACF/VTAM in the host processor to control network communications. NCP can also communicate with multiple hosts using local channel or remote links (PU type 5 or PU type 4) thus enabling cross domain application communication. In a multiple mainframe SNA environment, any terminal or application can access any other application on any host using cross domain logon. See also Emulator program.