SNAX/HLS Diagnosis and Support Manual

Glossary
104706 Tandem Computers Incorporated Glossary–3
DTE. See data-terminal equipment.
EIO. See execute I/O.
EMS. See event management service.
event. An event is an uncontrolled or unplanned transmission. Critical events are
those conditions that applications cannot handle and that cause processes or even
sessions to terminate. Noncritical events are conditions that applications can handle
and from which they can recover. Action events are those events that require operator
intervention.
Event Management Service. The event management service is part of Tandem’s
distributed management service software and it acts as the interface for alarms,
messages, and other events coming from SNAX/HLS and going to the application.
See also distributed system management. See also subsystem programmatic interface.
execute I/O (EIO). A machine instruction on the Tandem processor that initiates a
transfer over the I/O channel.
expand network. A network consisting of Tandem systems interconnected by
communication links and supported by Expand software.
finite state machine. Controls the transition of an object for example, a SNA session
between a finite number of states, each state transition being generated by one of a
finite number of events.
FMD. Function management data. A RU category used for user data exchanged
between LUs and for requests and responses exchanged between LUs, PUs, and SSCPs
at the network services layer of SNA.
FMH. Function Management Header. FM headers are typically used on sessions
involving LU session type 1, where they convey control information.
gateway LU. A LU subordinate to a gateway line on a gateway system. SNAX/XF
transparently handles the passing of information between gateway LUs and the
processes and devices residing on a Tandem system.
gateway system. A Tandem system that has a SNAX/XF communications link to an
SNA host. (SNAX/CDF is not defined as a gateway in a cross-domain environment.)
gateway PU. A PU subordinate to a gateway line on a gateway system.
HDLC LAPB. High-level data link control link access protocol–balanced.
HLS. See SNAX/High Level Support.
HLSCOM. An operational control tool that provides a command process for
SNAX/HLS. HLSCOM is the set of online commands that programmers can use to
control operations, analyze errors, and improve system performance. HLSCOM
communicates with SNAX/HLS through the Subsystem Programmatic Interface (SPI),
which is part of Tandem’s distributed systems management (DSM) software.