SNAX/XF LU Network Services Manual

Glossary
Glossary–6 097841 Tandem Computers Incorporated
primary logical unit (PLU). The logical unit (LU) 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. Within the context of the Tandem NonStop system, a process is a unique
execution of a program code module. The The Tandem NonStop Kernel is a collection
of cooperating processes that use a common message system.
process identification number (PIN). An unsigned integer that identifies a process in a
particular processor.
process pair. Two processes that include an active primary process, and a secondary
backup process in another CPU that is ready to take over if the primary process fails.
programmatic interface. A means for a program to communicate with another program.
PRT. See PRT protocol.
PRT protocol. A high-level 3270 protocol that allows a calling process to send
information one line at a time to an SNA 3270-type printer. The calling process sends
text only; SNAX/XF adds any necessary printer control characters to the outgoing text.
PS. Presentation services (one of the SNA functional layers).
PU. See physical unit.
PUCP. Physical unit control point.
PU object type. A Tandem object type that defines the various adjacent SNA physical
units with which SNAX/CDF can communicate.
PVC. Permanent virtual circuit.
QLLC. IBM Qualified Logical-Link Control protocol.
response message. An SPI message sent from a subsystem to an application program in
reaction to a command message. A message always contains entire response records
(a single response record cannot be split across multiple messages). If there are
multiple records in a response message, each record is enclosed in a data list.
return code. A value returned at the completion of a command, indicating whether the
command was successful and, if not, the reason for failure.
SCF. See Subsystem Control Facility.
SCP. See Subsystem Control Point.
SDLC. Synchronous data link control.
secondary logical unit (SLU). One of the two LUs involved in an LU-LU session. The SLU
functions under the control of the PLU, and accepts an incoming BIND request from a
PLU.
session. An SNA session is a temporary data path consisting of a physical and a logical
connection between two LUs in separate domains for information exchange. To