gtpd3m0qLibrary Guide with Master Index and Glossary

N

named pipe
Synonym for FIFO special file (so named because it is a pipe that is located in the file system by its name so that different processes can find it).

namespace
A unique identifier used for qualifying element and attribute names used in XML. A namespace allows you to retain unique element names by simply providing a two-part naming system through the use of element names associated with a Universal Resource Identifier (URI). The specific location may not actually contain any data about the tags, but simply allows more than one use of a specific tag name. For example, if you are using more than one DTD and both have a <firstname> element, you can distinguish between the two by using namespaces. For more information, go to the W3C Web site (http://www.w3.org/).

NAT
Network address table.

native console
A locally attached system console.

NAU
Network addressable unit.

NCB
Node control block.

NCB control record
A fixed-file record that contains information about the node control block (NCB) directory records.

NCB directory record
A fixed-file record that contains the names of dynamic LU resources and the addresses of the 381-byte long-term pool file node control block (NCB) records assigned to those resources.

NCB reconciliation function
A function that returns to the TPF system the node control block (NCB) directory record entries and NCB records that are no longer being used.

NCB reorganization function
A function that changes the number of node control block (NCB) directory records in the TPF system.

NCB slot
A field in an node control block (NCB) directory record entry that contains the address of a 381-byte long-term pool file NCB record for a dynamic LU resource. There are 8 NCB slots for each dynamic LU resource.

NCE
Network connection endpoint.

NCP
Network Control Program.

NEF
Network extension facility.

nested scope
In TPF transaction services, a commit scope within a commit scope. A nested commit scope begins when a higher-level commit scope is already active.

network address table (NAT)
The SNA table that contains the network addresses of all local TPF LUs and remote LUs that the TPF system has discovered dynamically.

network addressable unit (NAU)
In SNA, a logical unit, physical unit, or system services control point; it is the origin or the destination of information transmitted by the path control network.

network byte order
The byte order required for all binary integers in TCP/IP headers as they traverse a network. In this format, the 4 bytes in a 32-bit value are transmitted in the following order: bits 0-7 first, then bits 8-15, then bits 16-23, and bits 24-31 last. Machines that store binary integers in other formats must convert the header values into the network byte order before transmitting the data. See also host byte order and dotted decimal notation.

network connection endpoint (NCE)
The component in a high-performance routing (HPR) endpoint that processes network layer packets (NLPs) received over rapid transport protocol (RTP) connections. The last label in the automatic network routing field (ANRF) is always an identifier for an NCE in the destination node.

Network Control Program (NCP)
An IBM licensed program that provides communications controller support for single-domain, multiple-domain, and interconnected network capability.

network extension facility (NEF)
An extension of ACF/NCP/VS (a separate IBM licensed program) that allows ALC devices to attach to a 37x5 running under NCP control.

network layer header (NHDR)
The part of the network layer packet (NLP) that contains the automatic network routing (ANR) labels, among other information, and is used by the network to route the NLP from one rapid transport protocol (RTP) endpoint to another.

network layer packet (NLP)
A message unit used to carry data between high-performance routing (HPR) nodes. An NLP contains a network layer header (NHDR), transport header (THDR), and optionally data.

new-line character
A control character that causes the print or display position to move to the first position on the next line. This control character is represented by '\n' in the C language.

NHDR
Network layer header.

NLP
Network layer packet.

node
An endpoint of a link or a junction common to two or more links in a network. Nodes can be processors, controllers, or workstations, and they can vary in routing and other functional capabilities. (OSF) In a tree structure, a point at which subordinate items of data originate. (A) In SNA, an endpoint of a link or a junction common to two or more links in a network. Nodes can be distributed to host processors, communication controllers, or terminals. Nodes can vary in routing and other functional capabilities. In ACF/VTAM, a point in a network defined by a symbolic name.

node control block (NCB) record
A record that contains information about the message queues for an LU resource.

nonavailable state
The state a coupling facility (CF) is in when only certain CF commands are processed normally; all other CF commands are suppressed. Contrast with available state. See coupling facility (CF).

nonblocking mode
Control is returned to the caller of a socket API function even if its request is not satisfied. For example, for a read or recvfrom function call, the operating system does not suspend the application program if data is not available to satisfy the request. However, a return code of -1 is returned to the application program. See blocking mode.

nonduplicated file
A design for a TPF database where none of the records have duplicate copies.

nonfresh load
The part of SNA restart that is activated on most hardware and software IPLs. All SNA tables will be reloaded from their file copies. Contrast with fresh load.

nonpersistent message
A message that does not survive a restart of the queue manager. Contrast with persistent message.

nonunique collections
Collections that can contain elements that have the same value (such as bags and logs) or the same key (such as dictionaries and key bags).

NORM state
The most active of the 5 system states. All functions are available, communication lines are active, and all types of entries are processed.

notify lock structure
On a coupling facility (CF) this structure maintains lock granted and lock contention information.

NPSI
X.25 NCP Packet Switching Interface.

NSI
Next sequential instruction.

NULL
A pointer guaranteed not to point to a data object.

null character (NULL)
The character with the hex value 00 (all bits turned off).

null statement
A C statement that consists solely of a semicolon.