APN Event Management Programming Manual

Glossary

SNAX/XF and SNAX/APN Event Management Programming Manual—426859-001

Glossary-13

physical unit (PU)

physical unit (PU). That part of a device (hardware or software) that provides control

functions for its own node and for the other less intelligent device nodes attached to the

PU.

PIU. See path information unit (PIU)

PLU. See primary logical unit (PLU)

port. An entity that provides a SNAX/XF or SMNAX/APN line with access to an X25AM

subdevice or a TLAM session. The X25AM subdevice provides access to an X.25

network using the QLLC protocol.

primary logical unit (PLU). In SNA and SNAX/XF, the logical unit that controls an LU-LU

session. Within each LU-LU session, one of the LUs is the primary and the other is the

secondary. The most important control that the PLU exerts is the formatting and sending

of the BIND request that initiates the session.

process. A unique execution of a program. The Compaq NonStop™ Kernel allows a

collection of processes to cooperate by using a common message system.

process pair. Two processes: a primary process that is active, and a secondary, backup

process in another CPU that is ready to take over if the primary process fails.

programmatic command. A command issued by a program rather than by a human operator.