SNAX/APC Configuration and Management Manual

Glossary
SNAX/APC Configuration and Management Manual—138787
Glossary-10
request unit
request unit. In SNA, a message unit that contains control information such as a request
code, or function management headers, end-user data or both.
resource control block (RCB). A control block that represents the connection of a
transaction program to a half-session.
response unit. In SNA, a message unit that acknowledges a request unit. It may contain
additional information in response to the request.
return code (RC). A value returned at the completion of a command, indicating whether the
command was successful and, if not, the reason for failure.
RH. Request/response header.
RID. Resource ID.
RU. Request/response unit.
SCF. See Subsystem Control Facility (SCF)
.
SCREEN COBOL. A procedural language developed by Tandem and based on COBOL that
is used to define and control screen displays on terminals and other input/output devices.
SCREEN COBOL allows programmers to write requester programs that communicate
with operator terminals and intelligent input/output devices, and that send data to server
processes which manage application databases. SCREEN COBOL programs are
compiled into pseudocode form by the SCREEN COBOL compiler and then interpreted
by the TCP (terminal control process).
SDLC. Synchronous data link control.
SDT. Start data traffic request.
secondary logical unit (SLU). One of the two LUs involved in a LU-LU session. The SLU
functions under the control of the remote PLU. It accepts an incoming BIND request
from the PLU.
sense data. In SNA, the data sent with a negative response, indicating the reason for the
response.
ServerNet system area network (ServerNet SAN). A wormhole-routed, full-duplex,
packet-switched, point-to-point network designed with special attention to reducing
latency and ensuring reliability. The ServerNet SAN provides the communication path
used for interprocessor messages and for communication between processors and I/O
devices.
ServerNet wide area network (SWAN) concentrator. A Tandem data communications
peripheral that provides connectivity to a Himalaya S-series server. The SWAN
concentrator supports both synchronous and asynchronous data over RS-232, RS-449,
X.21, and V.35 electrical and physical interfaces.