OSI/AS Management Programming Manual

Glossary
056785 Tandem Computers Incorporated Glossary-13
Network service access point. See NSAP or NSAP address.
Noncritical event. A DSM event not to crucial to system or network operations. Each
subsystem determines which of its events are noncritical, by setting the value of the
emphasis token to FALSE. Compare critical event.
Nonsensitive command. A DSM command that can be issued by any user or program
allowed access to the target subsystem—that is, a command on which the subsystem
imposes no further security restrictions. For Tandem data communications
subsystems, the nonsensitive commands are all those that cannot change the state or
configuration of objects (usually information commands). Compare sensitive
command.
Nowait mode. In Guardian 90 file-system operations and in some APS operations, the
mode in which the called procedure initiates an I/O operation but does not wait for it
to complete before returning control to the caller. To have the called procedure wait
for the completion of the operation, the application calls a separate procedure
(AWAITIOX for the OSI/TS programmatic interface; MFM_AWAITIOX_ for the
OSI/AS interface). Compare wait mode.
NSAP (network service access point). The logical point at which Network Layer services
are provided by the Network Layer entity to the Transport Layer entity.
NSAP address. The global, network-unique address of an end system’s network service
access point, through which Network Layer services are provided.
NSP (network service provider) process. A process in the OSI subsystem that performs
service and protocol functions for the Network Layer and, for LANs, some functions
of the Data Link Layer. NSP processes are provided by the underlying X25AM and
TLAM subsystems.
Null value. A value indicating that a program has made no explicit assignment to a
variable or field. In DSM programmatic interfaces, a field of a structure has a null
value if the application has made no explicit assignment to that field after calling the
SSNULL procedure to initialize the structure.
Object. (1) One or more of the devices, lines, processes, and files in a Tandem
subsystem; any entity subject to independent reference or control by one or more
subsystems.
(2) In DSM, an entity subject to independent reference and control by a subsystem:
for example, the disk volume $DATA or the data communications line $X2502. An
object typically has a name and a type known to the controlling subsystem.
Object type. In DSM, the category of objects to which a specific object belongs: for
example, a specific disk file might have the object type FILE, and a specific terminal
might have the object type SU (subdevice). A subsystem identifies a set of object types
for the objects it manages. The SCF interfaces to Tandem data communications
subsystems use standard keywords to identify the types. The corresponding
programmatic interfaces have object-type numbers (represented by symbolic names
such as ZCOM-OBJ-SU) suitable for passing to the SPI SSINIT procedure.