A

A programming language used for mathematical calculations that requires a number of special characters (APL characters) representing mathematical operators. The SNAP-IX 3179G emulation program supports APL characters in addition to the standard 3270 characters.

A character string that contains characters from the following groups only: uppercase A-Z, numeric digits 0-9, #, $, and @.

The abnormal end of a task.

The ending of a task before its completion because of an error condition that recovery facilities cannot resolve while the task is running.

In SNA, a command used to start a session on a logical unit (a request to activate an SSCP-LU session).

In SNA, a command used to start a session on a physical unit (request to activate SSCP-PU session).

A form of session-level pacing in which session components exchange pacing windows that may vary in size during the course of a session. This allows transmission within a network to adapt dynamically to variations in availability and demand of buffers on a session-by-session basis. Session-level pacing occurs within independent stages along the session path according to local congestion at the intermediate nodes and endpoint nodes.

In the Internet suite of protocols, the protocol that dynamically maps an IP address to an address used by a supporting metropolitan or local area network such as Ethernet or token-ring.

In a network, pertaining to devices, nodes, programs, or domains that are directly connected by a data link or that share common control.

Two nodes connected together by at least one path that passes through no other node.

A group of programs licensed by IBM (principally ACF/VTAM and ACF/NCP) that uses the concepts of Systems Network Architecture (SNA), including distribution of function and resource sharing.

An IBM program that provides communication controller support for single-domain, multiple-domain, and interconnected network capability.

An extension to SNA featuring (a) greater distributed network control that avoids critical hierarchical dependencies, thereby isolating the effects of single points of failure; (b) dynamic exchange of network topology information to foster ease of connection, reconfiguration, and adaptive route selection; (c) dynamic definition of network resources; and (d) automated resource registration and directory lookup. APPN extends the LU 6.2 peer orientation for end-user services to network control and supports multiple LU types, including LU 0, LU 1, LU 2, LU 3, and LU 6.2.

The general facility characterizing the LU 6.2 architecture and its various implementations in products.

Sometimes used to refer to the LU 6.2 architecture and its product implementations as a whole, or to an LU 6.2 product feature in particular, such as an APPC application programming interface.

A character string that contains characters from the following groups only: uppercase A-Z, lowercase a-z, numeric digits 0- 9, . (period),#, $, and @.

See attention identification key.

A message sent to a management services focal point in a network to identify a problem or an impending problem.

An alternative name used for a network name, or other network entity.

To assign a resource, such as a disk or diskette file, to perform a task.

An LU 6.2 application programming interface (API) verb used to assign a session to a conversation for the conversation's use.

Contrast with deallocate.

The standard code, using a coded character set consisting of 7-bit coded characters (8-bits including parity check), that is used for information interchange among data processing systems, data communication systems, and associated equipment. The ASCII set consists of control characters and graphic characters. (A)

An organization consisting of producers, consumers, and general interest groups, that establishes the procedures by which accredited organizations create and maintain voluntary industry standards in the United States. (A)

The set of programming language constructs or statements that can be coded in an application program to obtain the specific functions and services provided by an underlying operating system or service program.

A program written for or by a user to process the user's application; in an SNA network, a user of a type 6.2 logical unit. Contrast with service transaction program.

A node that implements the APPN Branch Extender function, to simplify large APPN networks by separating out resources in different locations (for example in separate branches of a large organization). It appears as an APPN end node to the main APPN backbone network, and as an APPN network node to the end nodes in the branch.

A collection of tasks that provide directory and route selection functions for advanced peer-to-peer networking (APPN). An end node control point provides its own configuration, session, and management services with assistance from the control point in its serving network node. A network node control point also provides session and routing service.

A node that provides a broad range of end-user services and supports sessions between its local control point (CP) and the CP in an adjacent network node. It uses these sessions to dynamically register its resources with the adjacent CP (its network node server), to send and receive directory search requests, and to obtain management services.

A collection of interconnected network nodes and their client end nodes.

A node that offers a broad range of end-user services and that can provide the following:

• Distributed directory services, including registration of its domain resources to a central directory server

• Topology database exchanges with other APPN network nodes, enabling network nodes throughout the network to select from optimal routes for LU-LU sessions based on requested classes of service.

• Session services for its local LUs and client end nodes

• Intermediate routing services within an APPN network

The operation of an application programming interface (API) function that enables the interface to return control to the application before processing of the verb has completed so that the application can continue with further processing while the function may complete later. See also nonblocking mode.

A computer terminal that uses asynchronous signals to communicate with a host machine.

A request to start a conversation, sent from an invoking transaction program to an invoked transaction program.

Information configured on a local LU that specifies where the application is to be started and can also define a timeout for the local application to accept the incoming conversation. Specifying a timeout ensures that the remote application is notified in case of errors that prevent the local application from starting.

A 3270 control key (such as PF1, CLEAR, or ENTER) that causes data to be sent from a device to the mainframe.

A log file in which SNAP-IX keeps a record of normal system events. Contrast with error log.

In High-Performance Routing (HPR), a highly efficient routing protocol that minimizes cycles and storage requirements for routing network layer packets through intermediate nodes on the route.

B

In multiprogramming, the conditions under which noninteractive programs are run. Contrast with foreground.

A process that does not require operator intervention but can be run by the computer while the workstation is used to do other work.

A mode of program execution in which the shell does not wait for program completion before prompting the user for another command.

Contrast with foreground process.

A configuration server that holds a copy of the SNAP-IX domain configuration but not the master copy. It can take over as the master server if the current master server becomes unavailable. See also configuration server and master server.

Data rate transfer in K bits, K bytes, M bits, and M bytes per second.

An LU 6.2 conversation type specified by the allocating transaction program. Transaction programs using basic conversation have available to them a wider variety of LU 6.2 functions, but they are responsible for more of their own error recovery and must manage details of the data stream used on the conversation.

In SNA, the unit of data and control information passed between half-sessions. It consists of a request/response header (RH) followed by a request/response unit (RU).

In SNA, the unit of data and control information passed between path control components. A BTU can consist of one or more path information units (PIUs). Each PIU consists of a transmission header (TH) followed by a basic information unit (BIU) or a BIU segment.

A processing method in which a program executes with little or no operator action. This is a background process.

The number of changes in signal levels, frequency, or phase per second on a communication channel. If each baud represents 1 bit of data, baud is the same as bits per second. However, it is possible for one signal change (1 baud) to equal more than 1 bit of data.

A unit of signaling speed equal to the number of discrete conditions or signal events per second. For example, 1 baud equals one-half dot cycle per second in Morse code, 1 bit per second in a train of binary signals, and one 3-bit value per second in a train of signals that can each assume one of eight different states.

In asynchronous transmission, the unit of modulation rate corresponding to one unit interval per second; for example, if the duration of the unit interval is 20 milliseconds, the modulation rate is 50 baud.

An attempt by a logical unit (LU) to gain control of a contention-loser session in order to transmit data.

Pertaining to a system of numbers to the base two.

A unit in the binary numbering system. The only permissible values for binary digits are 0 and 1. Synonymous with bit.

A file that contains codes that are not part of the ASCII character set. Binary files can utilize all 256 possible values for each byte in the file.

A form of telecommunication line control that uses a standard set of transmission control characters and control character sequences, for binary synchronous transmission of binary-coded data between stations.

Contrast with synchronous data link control (SDLC).

In SNA, the session parameters that the system services control point (SSCP) sends to the primary logical unit (PLU) and the PLU sends in the BIND request to the secondary logical unit (SLU); these parameters specify the proposed protocol options for an LU-LU session.

One of the two communication security passwords. In an LU-LU session, it is the password that the system checks against the remote system to verify that it is who it claims to be. See also node verification and session-level security.

In SNA products, a request to activate a session between two logical units.

Synonym for binary digit.

In data communications, data that is recorded, processed, or sent as a unit.

A way of requesting a service over an interface so that if the request cannot be completed immediately, the requesting process is suspended until the request is completed.

Contrast with nonblocking mode.

A binary numbering system named after mathematician George Boole in which zero and one are the only two values that can be returned. Traditionally, a value of zero represents FALSE while a value of one represents TRUE. See also binary.

A small program that loads larger programs during system initialization.

In SNA, a capability of a subarea node to provide protocol support for attached peripheral nodes, such as: (a) interconnecting subarea path control and peripheral path control elements, (b) performing session sequence numbering for low-function peripheral nodes, and (c) providing session-level pacing support.

In SNA, the component that provides these capabilities.

In SNA, a subarea node with boundary function. A subarea node may be a boundary node, an intermediate routing node, both, or neither, depending on how it is used in the network.

In SNA, one or more chains of request units and their responses, which are exchanged between two session partners and represent a transaction between them. A bracket must be completed before another bracket can be started. Examples of brackets are data base inquiries and replies, update transactions, and remote job entry output sequences to workstations.

An APPN function that simplifies large APPN networks by separating out resources in different locations (for example in separate branches of a large organization). This reduces the amount of topology information that must be maintained, while still allowing efficient resource location. See also APPN branch network node.

See APPN branch network node.

A functional unit that interconnects two local area networks that use the same logical link control protocol but may use different medium access control protocols.

A functional unit that interconnects multiple LANs (locally or remotely) that use the same logical link control protocol but that can use different medium access control protocols. A bridge forwards a frame to another LAN based on the medium access control (MAC) address.

In the connection of local loops, channels, or rings, the equipment and techniques used to match circuits and to facilitate accurate data transmission.

Contrast with gateway and router.

Simultaneous transmission of data to more than one destination.

The simultaneous propagation of a search request to all network nodes in an APPN network. This type of search may be used when the location of a resource is unknown to the requester. Contrast with directed search .

Berkeley Software Distribution of the UNIX operating system.

A routine or storage used to compensate for a difference in rate of flow of data, or time of occurrence of events, when transferring data from one device to another. (A)

A portion of storage used to hold input or output data temporarily.

An error in a program or a logic problem in the intent of the program.

A facility for transferring data between devices.

A mechanism on a pointing device, such as a mouse, used to request or initiate an action or a process.

A graphical device that identifies a choice.

A graphical mechanism that, when selected, performs a visible action. For example, when a user clicks on a list button, a list of choices appears.

A group of 8 adjacent binary digits that can represent one ASCII or EBCDIC character.

C

A buffer storage that contains frequently accessed instructions and data; it is used to reduce access time.

An optional part of the directory database in network nodes where frequently used directory information may be stored to speed directory searches.

In SNAP-IX, a routine specified by an application program that issues a verb that uses asynchronous completion. When the verb completes, SNAP-IX uses the callback routine to notify the application.

Synonymous with callback function.

Synonym for callback.

In X.25 communications, data optionally included in the call-request packet by the user application.

A protocol used on Ethernet LANs that requires carrier sense and in which a transmitting data station that detects another signal while transmitting, stops sending, sends a jam signal, and then waits for a variable time before trying again. (A)

Able to distinguish between uppercase and lowercase letters.

A vacuum tube in which a beam of electrons can be moved to draw lines or to form characters or symbols on its luminescent screen.

High-capacity read-only memory in the form of an optically read compact disk.

A method of logging SNAP-IX error and audit messages in files only on the master server. Contrast with local logging.

The part of a computer that includes the circuits that control the interpretation and execution of instructions. A CPU is the circuitry and storage that executes instructions. Traditionally, the complete processing unit was often regarded as the CPU, whereas today the CPU is often a microchip. In either case, the centrality of a processor or processing unit depends on the configuration of the system or network in which it is used.

A group of request units delimited by begin-chain and end-chain. Responses are always single-unit chains.

In SNA, an indicator in the request header specifying that the sender has finished sending and is prepared to receive.

In SNA, a data flow control protocol in which the sending logical unit (LU) stops sending normal-flow requests, signals this fact to the receiving LU using the change-direction indicator, and prepares to receive requests.

A path along which signals can be sent, for example, data channel, output channel. (A)

On host systems, the communication path that connects to peripheral devices such as communication controllers.

A letter, digit, or other symbol.

The set of characters (alphabetic, numeric, punctuation, and special characters such as $ and #) that can be used in a particular situation (for example, the set associated with a particular national language). See also double-byte character set .

In error detection, a function of all bits in a block. If the written and calculated sums do not agree, an error is indicated.

Pertaining to a secured resource, either a file or library, that uses the user list of a parent resource. A child resource can have only one parent resource.

In the operating system, a child is a process, started by a parent process, that shares the resources of the parent process. Contrast with parent.

In the operating system, a process, started by a parent process, that shares the resources of the parent process. See also fork.

A language used to develop software applications.

A set of characteristics (such as route security, transmission priority, and bandwidth) used to construct a route between session partners. The class of service is derived from a mode name specified by the initiator of a session.

A system library that contains common C language functions.

A functional unit that receives shared services from a server.

In the SNAP-IX environment, a system that is dependent on a server to provide it with SNA communication functions.

A table, typically based on EBCDIC or ASCII, that defines the mapping between graphical characters and 8-bit numbers. Code pages vary slightly from country to country. Also used for a similar mapping between double-byte characters and 16-bit numbers.

The SNAP-IX program that enables the user to configure and manage the SNAP-IX system by entering commands at the Solaris command prompt.

To make all changes permanent that were made to one or more database files since the last commit or rollback operation, and make the changed records available to other users.

An application programming interface (API) designed to achieve openness as an industry standard for communications programming. CPI-C provides access to interprogram services such as (a) sending and receiving data and (b) synchronizing processing between programs. In an SNA environment, CPI-C also makes use of APPC protocols.

In addition to the standard C-language interface, SNAP-IX also provides a CPI-C interface for use by Java applications.

An application programming interface (API) provided by SNAP-IX that provides facilities for translating characters, logging messages, and tracing.

A device that directs the transmission of data over the data links of a network; its operation may be controlled by a program executed in a processor to which the controller is connected or it can be controlled by a program executed within the device.

A type of communication control unit whose operations are controlled by one or more programs stored and executed in the unit. It manages the details of line control and the routing of data through a network.

A part of a computer system that electrically or physically connects a computer or device to a data communications network.

A message displayed on the status line of the 3270 emulation program that indicates the status of the program's communication link with the host. The message appears as

-+z_nnn

nnn

A file that specifies the characteristics of a system device or network.

In a multiserver domain, any server selected to store replicated configuration information. The first available configuration server becomes the master server. See also master server and backup server .

A synchronization processing level, specified during allocation of a conversation, that enables a transaction program to solicit acknowledgment from its partner TP of a message sent to the partner TP. Contrast with sync point processing.

A representation within an APPN network of a shared-access transport facility (SATF), such as a token ring, that allows nodes identifying their connectivity to the SATF by a common virtual routing node to communicate. Nodes connected to the SATF can communicate with any other nodes connected to the SATF without needing to configure explicitly connectivity information between each pair of communicating nodes.

A service that establishes a logical connection between two partners for the duration that they want to communicate. Data transfer takes place in a reliable, sequenced manner. Contrast with connectionless service .

Synonym for connection-oriented service.

A network service that treats each packet or datagram as a separate entity that contains the source address and destination address and for which no acknowledgment is returned to the originating source. Connectionless services are on a best-effort basis and do not guarantee reliable or in-sequence delivery. Contrast with connection-oriented service.

Synonym for connectionless service.

An option used by a modem or SDLC adapter to hold the request-to-send (RTS) signal high constantly, forcing the other end of the connection to maintain clear-to-send (CTS) high. Selecting this option increases throughput by avoiding the delay required to raise RTS when needed and wait for CTS to be raised by the other end before sending any data. This option cannot be used on multidrop links.

In a session, a situation in which both NAUs attempt to initiate the same action at the same time, such as when both attempt to send data in a half-duplex protocol (half-duplex contention), or both attempt to start a bracket (bracket contention). At session initiation, one NAU is defined to be the contention winner; its action will take precedence when contention occurs. The contention loser must get explicit or implicit permission from the contention winner to begin its action.

A component of an APPN or LEN node that manages the resources of that node. In an APPN node, the CP is capable of engaging in CP-CP sessions with other APPN nodes. In an APPN network node, the CP also provides services to adjacent end nodes in the APPN network.

A component of a node that manages resources of that node and optionally provides services to other nodes in the network. Examples are a system services control point (SSCP) in a type 5 subarea node, a network node control point (NNCP) in an APPN network node, and an end node control point (ENCP) in an APPN or LEN end node. An SSCP and an NNCP can provide services to other nodes.

An IBM protocol used for communications with an IBM 3174 or 3274 Control Unit or other appropriate interface unit. In this protocol, a program in the workstation emulates a 3278 or 3879 terminal for a user at a virtual terminal, and the interface unit is responsible for enforcing the protocol.

Contrast with distributed function terminal (DFT).

An application programming interface (API) that allows access to host applications using any of the logical unit (LU) types 0, 1, 2, or 3. LUA provides access to the SSCP session as well as the LU session. See also Logical Unit Type 0 Application Programming Interface.

A logical connection between two transaction programs using an LU 6.2 session. Conversations are delimited by brackets to gain exclusive use of a session.

A security mechanism used on LU 6.2 conversations whereby the invoking transaction program (TP) specifies a user name and password that are validated before the invoked TP starts.

The condition of a conversation that reflects what the past action on that conversation has been and that determines what the next set of actions can be.

The type (basic or mapped) that determines how data is exchanged between two programs that use LU 6.2 protocols. See also basic conversation and mapped conversation.

The parallel sessions between two control points, using LU 6.2 protocols and a mode name of CPSVCMG, on which network services requests and replies are exchanged. Each control point of a given pair has one contention-winner session and one contention-loser session with the other.

An unexpected interruption of computer service, usually due to a serious hardware or software malfunction.

Synonym for default directory.

An IBM licensed program that enables transactions entered at remote terminals to be processed concurrently by user-written application programs. It includes facilities for building, using, and maintaining databases.

D

A program that runs unattended to perform a service. Some daemons are triggered automatically to perform their task; others operate periodically. An example is the Solaris cron daemon, which periodically performs the tasks listed in the /usr/spool/cron/crontabs directory.

In a data station, the equipment installed at the user's premises that provides all the functions required to establish, maintain, and end a connection, and the signal conversion and coding between the data terminal equipment (DTE) and the line.

In computer security, the National Institute of Standards and Technology (NIST) Data Encryption Standard, adopted by the U.S. government as Federal Information Processing Standard (FIPS) Publication 46, which allows only hardware implementations of the data encryption algorithm.

In SNA, a session-layer component that manages the communication between the half-sessions.

A self-contained block of data, used by connectionless services, that carries sufficient information to be routed across a network without relying on earlier exchanges. See also connectionless service

In SNA, synonym for link.

A set of rules used by nodes on a data link (such as an SDLC link or a token ring) to accomplish an orderly exchange of information.

An industry-standard interface between different levels of a link software component.

Synonym for DCE ready.

The information (data and control commands) transmitted over a data link.

That part of a data station that serves as a data source, data sink, or both. (A)

A signal to the modem used with EIA 232 protocol.

The movement, or copying, of data from one location and the storage of the data at another location.

In the EIA 232 standard, a signal that indicates to the data terminal equipment (DTE) that the local data circuit-terminating equipment (DCE) is connected to the communication channel and is ready to send data. Synonymous with data set ready (DSR).

In SNA, a request issued by a system services control point (SSCP) to a logical unit (LU) to terminate an SSCP-LU session. Contrast with ACTLU.

In SNA, a request issued by a system services control point (SSCP) to a physical unit (PU) to terminate an SSCP-PU session. Contrast with ACTPU.

An error condition in which processing cannot continue because each of two elements of the process is waiting for an action by or a response from the other.

To end the assignment of a resource, such as a disk or diskette file, when it is no longer required to perform a task.

An LU 6.2 application programming interface (API) verb used to close a conversation and end its association with a session.

Contrast with allocate.

To detect, locate, and correct errors in the configuration of a computer system or a software program.

A program or programs used to detect, trace, and eliminate errors in computer programs or software.

The directory name supplied by the operating system if none is specified. Synonymous with current directory.

A group of dependent type 6.2 logical units (LU) that can be used interchangeably by CPI-C and APPC applications. If an application does not specify which local LU it wants to use, SNAP-IX assigns the application an available LU from this pool, eliminating the need to configure which LU each application can use.

In SNA, a protocol requested in the Form of Response Requested field of the request header that directs the receiver of the request to return a response unconditionally, whether positive or negative. See also negative response and positive response.

An LU that requires assistance from a system services control point (SSCP) in order to initiate an LU-LU session. It requires an SSCP-LU session.

An APPN end node or an APPN network node that owns dependent logical units (LUs), but requests that a dependent LU server provide the SSCP services for those dependent LUs so that a session between dependent LUs can traverse an APPN network.

An APPN network node that provides SSCP services for a dependent LU in its own or another APPN network. Contrast with dependent LU requester.

In SNA, a field in the transmission header that contains the network address of the destination. Contrast with origin address field .

A collection of functions that control the interface between I/O device adapters and the processor.

The transfer of data between memory and an input/output device without processor intervention.

A search request sent to a specific destination node known to contain a resource, such as a logical unit, to verify the continued presence of the resource at the destination node and to obtain the node's connectivity information for route calculation. Contrast with broadcast search.

A table of identifiers and references to the corresponding items of data. (A)

Part of a file system that provides an index to the files that comprise that file system.

A database in an APPN node that lists names of resources (in particular, logical units) and records the CP name of the node where each resource is located.

A storage device made of one or more flat, circular plates with magnetic surfaces on which information can be stored.

The mechanism used to seek, read, and write information on a disk.

A thin, flexible magnetic plate that is permanently sealed in a semi-rigid protective cover. It can be used to store information.

The mechanism used to read and write information on diskettes.

A number between 2 and 5 that identifies a type of 3278 or 3279 video adapter and monitor. Model 2 is the standard display consisting of 24 rows and 80 columns. Models 3-5 are used for larger displays.

A 3270 emulation session between a local computer and a host that uses a logical unit (LU) type 2 session and emulates a 3278 or 3279 display.

A protocol used for communication between a terminal and an IBM 3274 or IBM 3174 control unit that allows multiple concurrent logical terminal sessions.

Contrast with control unit terminal (CUT) mode.

The physical unit (PU) in the node that provides dependent LU requester (DLUR) services.

The SNAP-IX local area network (LAN) system consisting of Solaris servers, each of which contains a node and its associated connectivity components, and Solaris or Windows clients, which access the node and connectivity components on a server across the LAN.

The SNAP-IX configuration file that contains the configuration of domain resources. Contrast with node configuration file.

A resource in the SNAP-IX system that applies to the complete SNAP-IX system rather than being associated with a particular node. The following are examples of domain resources:

• Information about 3270 users

• Information about invokable transaction programs (TPs)

• CPI-C side information

Contrast with node resource.

A set of characters in which each character is represented by 2 bytes. Languages such as Japanese, Chinese, and Korean, which contain more symbols than can be represented by 256 code points, require double-byte character sets. Because each character requires 2 bytes, the typing, display, and printing of DBCS characters requires hardware and programs that support DBCS.

In the direction of data flow from the host to the user.

From the processor toward an attached unit or end user.

A logical unit on a downstream computer that uses PU concentration or DLUR to access a host LU.

A physical unit (PU) on a downstream computer with which downstream LUs are associated. See also downstream LU

To copy data in a readable format from main or auxiliary storage onto an external medium such as tape, diskette, or printer.

Data that has been dumped.

Pertaining to communication in which data can be sent and received at the same time. Synonymous with full-duplex. Contrast with half-duplex .

A host feature that allows dependent logical units (LUs) served by a node to be added to the host configuration when the communications link from the node to the host is established, instead of requiring the LUs to be configured statically at the host. This feature reduces the initial configuration required at the host and makes later expansion easier.

When the communications link from SNAP-IX to a host is established, the host informs SNAP-IX whether it supports DDDLU. If the host supports DDDLU, SNAP-IX sends the information required to define the dependent LUs that use the link. If the host does not support DDDLU, SNAP-IX assumes that the LUs have been defined statically at the host and does not send any definition information.

A file containing executable code and data bound to a program at load time or run time, rather than during linking. The code and data in a dynamic link library are specific to variants of the Windows operating system and can be shared by several applications simultaneously.

A link station created in one of the following situations when no suitable link station connecting to the remote node is already configured on the local node:

• The local node is part of a connection network and needs to contact a remote node on the same connection network to activate a session.

• A remote node attempts to connect to the local node.

This link station cannot be modified and can be used only for sessions between independent logical units.

E

A program used to enter and modify programs, text, and other types of documents and data.

In data communication, a specification of the Electronic Industries Association (EIA) that defines the interface between data terminal equipment (DTE) and data circuit-terminating equipment (DCE), using serial binary data interchange.

In data communication, a specification of the Electronic Industries Association (EIA) that defines the electrical characteristics for balanced voltage digital interface circuits for the interchange of serial binary data between data terminal equipment (DTE) and data circuit-terminating equipment (DCE), or any point-to-point interconnection of serial binary signals between digital equipment. The international equivalent is CCITT Recommendation V.11.

The use of programming techniques and special machine features to permit a computing system to run programs written for another system.

Imitation. For example, when one computer imitates the characteristics of another computer.

A program (for example, a 3270 or 5250 emulation program) that causes a computer to act as a workstation attached to another system.

To scramble data or to convert data to a secret code that masks the meaning of the data to any unauthorized recipient.

A key used to encrypt or decrypt data.

See APPN end node.

Notification from a file system that the end of a file has been reached.

A mechanism to allow SNA communications over Internet Protocol (IP) networks, providing the benefits of High-Performance Routing (HPR) functionality for the SNA traffic. Also known as HPR/IP (HPR over IP).

A variable that specifies how an operating system or another program will run.

A file in a product or system where error information is stored for later access.

An indication that an error has been detected.

A set of routines that attempt to recover from transmission errors.

In shell programming and TTY programming, the \ (backslash) character, which indicates that the next character is not intended to have the special meaning normally assigned to it.

In general, a character that suppresses or selects a special meaning for one or more characters that follow.

A character that is preceded by a \ (backslash) and is interpreted to have a special meaning to the operating system.

A sequence sent to a terminal to perform actions such as moving the cursor, changing from normal to reverse video, and clearing the screen. In Solaris, the terminfo file defines these escape sequences.

A local area network that allows multiple stations to access the transmission medium at will without prior coordination, avoids contention by using carrier sense and deference, and resolves contention by using collision detection and delayed retransmission. Ethernet uses carrier sense multiple access with collision detection (CSMA/CD).

An occurrence of significance to a task; for example, an SNMP trap, the opening of a window or a submap, or the completion of an asynchronous operation.

In programming languages, an abnormal situation that may arise during the running of a program, perhaps causing a deviation from the normal run sequence, and for which handling facilities exist.

Contrast with interrupt and signal .

In remote job entry (RJE), data that is transferred in records of up to 128 bytes, as opposed to standard data, which is transferred in records of up to 80 bytes.

An remote job entry (RJE) output device, similar to a punch device, except that it can process data in records of up to 128 bytes instead of up to 80 bytes, which is the maximum record length for a standard punch device.

A specific type of basic link unit that is used to convey node and link characteristics between adjacent nodes. XIDs are exchanged between link stations before and during link activation to establish and negotiate link and node characteristics, and after link activation to communicate changes in these characteristics. See also format 0 XID and format 3 XID.

To overlay the current process with another executable program. See also fork.

A file that contains programs or commands that perform operations on actions to be taken.

A program that can be run as a self-contained procedure. It consists of a main program and, optionally, one or more subprograms.

A code developed for the representation of textual data. EBCDIC consists of a set of 256 eight-bit characters.

In data communications, the ability of a modem to provide data clocking.

F

An American National Standards Institute (ANSI) standard for a 100-megabit-per-second LAN using optical fiber cables.

A name assigned or declared for a file.

The user who has the highest level of access authority to a file, as defined by the file.

In remote communications, the transfer of a file or files from one system to another over a data link.

In the Internet suite of protocols, an application layer protocol that uses TCP and Telnet services to transfer bulk-data files between machines or hosts.

The half-session defined at session activation as (a) able to begin a bracket without requesting permission from the other half-session to do so and (b) winning contention if both half-sessions attempt to begin a bracket simultaneously. Synonym for contention-winner session.

A modifier that appears on a command line with the command name that defines the action of the command. A dash usually precedes a flag.

In data communication, control of the data transfer rate.

In SNA, the process of managing the rate at which data traffic passes between components of the network. The purpose of flow control is to optimize the rate of flow of message units with minimum congestion in the network; that is, to neither overflow the buffers at the receiver or at intermediate routing nodes, nor leave the receiver waiting for more message units.

For any given management services discipline (for example, problem determination or response time monitoring), the control point that is responsible for that type of network management data for a sphere of control. This responsibility may include collecting, storing, or displaying the data, or all of these. (For example, a problem determination focal point is a control point that collects, and that may store or display, problem determination data.)

A family of characters of a given size and style; for example, 9-point Helvetica.

In multiprogramming, the environment in which programs that interact with users are run. Contrast with background.

A process that must run to completion before another command is issued to the shell. The foreground process is in the foreground process group, which is the group that receives the signals generated by a terminal. Contrast with background process.

To create and start a child process.

A defined arrangement of such things as characters, fields, and lines, usually used for displays, printouts, or files.

A format of an exchange identification (XID) that does not contain a CP name. The sender is identified only by the node identifier (node ID).

A format of an exchange identification (XID) that contains a CP name and a node identifier (node ID).

An entry in the SNAP-IX configuration file that determines a page layout used to format remote job entry (RJE) output sent to a printer device. The FCB determines parameters such as the page length and top and bottom margins.

The unit of transmission in some networks, including Token-Ring and SDLC. The unit includes delimiters, control characters, information, and checking characters.

In X.25 communications, the level between the physical level and the packet level, which works according to the high-level data link control procedure (HDLC). Synonymous with data-link level and level 2. See packet level.

An interface standard describing the boundary between a user's equipment and a fast-packet network. In frame-relay systems, flawed frames are discarded; recovery comes end-to-end rather than hop-by-hop.

A technique derived from the integrated services digital network (ISDN) D channel standard. It assumes that connections are reliable and dispenses with the overhead of error detection and control within the network.

A dedicated communications processor that is used to offload communications functions from the host.

Synonym for duplex.

In SNA, a name that uniquely identifies a specific resource (such as an LU or a CP) within a specific network. It consists of a network identifier and a resource name, each of which is a 1- to 8-byte symbol string. The network identifier and resource name are separated by a period (.).

A subroutine that returns the value of a single variable, such as subroutines that compute mathematical functions.

An expression that moves the path of execution from the current function to a specified function and evaluates to the return value provided by the called function. A function call contains the name of the function to which control moves and a parenthesized list of values.

Keys that request actions but do not display or print characters. This includes the keys that normally produce a printed character, but produce a function instead when used with the code key.

In SNA, an RU category used for end-user data exchanged between logical units (LUs) and for requests and responses exchanged between network services components of LUs, PUs, and SSCPs.

One or more headers, optionally present in the leading request units (RUs) of an RU chain, that allow one LU to (a) select a transaction program or device at the session partner and control the way in which the end-user data it sends is handled at the destination, (b) change the destination or the characteristics of the data during the session, and (c) transmit between session partners status or user information about the destination (for example, a program or device). Function management headers can be used with LU type 0, 1, 4, 6.0, and 6.2 protocols.

In SNA, a specification of various data flow control protocols (such as RU chains and data flow control requests) and FMD options (such as use of FM headers, compression, and alternate codes) supported for a particular session. Each function management profile is identified by a number.

G

A functional unit that interconnects two computer networks with different network architectures. A gateway connects networks or systems of different architectures. A bridge interconnects networks or systems with the same or similar architectures.

A functional unit that connects two networks or subnetworks having different characteristics, such as different protocols or different policies concerning security or transmission priority.

The data stream used for conversations in LU 6.2 sessions.

1,073,741,824 in decimal notation when referring to memory capacity; in all other cases, it is defined as 1,000,000,000 (one billion).

A collection of users who can share access authorities for protected resources.

A number that corresponds to a specific group name. The group ID can often be substituted in commands that take a group name as a value.

A name that uniquely identifies a group of users to the system.

H

Pertains to communications in which data can be sent in only one direction at a time. Contrast with duplex.

A normal-flow send/receive mode in which one half-session sets the Change Direction indicator in the RH on an end of chain to allow the other half-session to begin sending.

A session-layer component consisting of the combination of data flow control and transmission control components comprising one end of a session.

A data structure that is a temporary local identifier for an object.

The physical equipment of computing and computer-directed activities. The physical components of a computer system.

System-defined control information that precedes user data.

A collection of dynamically allocated variables.

A choice that gives a user access to helpful information about objects, choices, tasks, and products. A Help choice can appear on a menu bar or as a push button.

A file, separate from the source code of a program, that contains help definitions in a special help format that the operating system can use.

A unit of frequency equal to one cycle per second.

Pertaining to a system of numbers to the base 16; hexadecimal digits range from 0 through 9 and A through F, where A represents 10 and F represents 15.

In data communications, the use of a specified series of bits to control data links in accordance with the International Standards for HDLC: ISO 3309 Frame Structure and ISO 4335 Elements of Procedures. This DLC is similar to synchronous data link control (SDLC).

An application programming interface that provides a way for users and programmers to access the presentation space of a 3270 or 5250 emulator.

Most significant; leftmost. For example, the digit 5 in the number 526819.

An addition to APPN that enhances data-routing performance and session reliability.

See also automatic network routing (ANR) and Rapid Transport Protocol (RTP).

Contrast with intermediate session routing (ISR).

A directory associated with an individual user.

The user's current directory after login or after issuing the cd command with no argument.

In Internet communications, the number of routers that a datagram passes through on its way to its destination.

In SNA, a measure of the number of links to be traversed in a path to a destination.

In the Internet suite of protocols, an end system. The end system can be any workstation; it does not have to be a mainframe.

In SNA, the primary or controlling computer in a communications network, typically a mainframe.

In SNA, a subarea node that contains a system services control point (SSCP).

The amount of time a host computer takes to reply to a message sent to it by a 3270 emulation program. See also response time monitor and last transaction time indicator.

The key combination used to change from one session to another on the workstation.

To jump from a host session to an application on the workstation, or from the workstation to the host session.

A way of presenting information online with connections between one piece of information and another. These connections are called hypertext links. Thousands of these hypertext links enable you to explore additional or related information throughout the online documentation. See also hypertext link.

A connection between one piece of information and another. In the graphics interface, the link is displayed in a rectangular box, and in the ASCII interface, it is displayed as underlined text. When you select one of these links, you are taken to a target piece of information that is then displayed.

I

A graphic symbol, displayed on a screen, that a user can point to with a device such as a mouse in order to select a particular function or software application.

Institute of Electrical and Electronics Engineers.

An IEEE standard describing how data is formatted into frames for LAN transmission.

Ethernet LAN specification.

Token Ring LAN specification.

Fiber Distributed Data Interface specification.

A text file that contains declarations used by a group of functions, programs, or users.

In X.25 communications, a call arriving at the data terminal equipment (DTE).

An IBM file transfer program that operates in the CICS, VM/CMS, and MVS/TSO environments and enables files to be transferred between a local computer and the host.

An LU that is able to activate an LU-LU session (that is, send a BIND request) without assistance from an SSCP. It does not have an SSCP-LU session. Currently, only an LU 6.2 can be an independent LU.

Synonym for Information Management System/Virtual Storage (IMS/VS).

A database/data communication (DB/DC) system that can manage complex databases and networks. Synonymous with IMS.

The initialization procedure that causes an operating system to commence operation.

A facility for entering characters from double-byte character sets using a standard keyboard.

Pertaining to input, output, or both between a computer and a device.

A type of intermediate routing function within an APPN network node that provides session-level outage reporting and flow control for all routes passing through the node but whose end points are elsewhere.

Contrast with automatic network routing.

The internet administered by the Internet Architecture Board (IAB), consisting of large national backbone networks and many regional and campus networks all over the world. The Internet uses the Internet suite of protocols.

A connectionless protocol that routes data through a network or interconnected networks. IP acts as an intermediary between the higher protocol layers and the physical network.

The process by which programs communicate data to each other and synchronize their activities. Semaphores, signals, and internal message queues are common methods of interprocess communication.

A suspension of a process, such as execution of a computer program caused by an external event, and performed in such a way that the process can be resumed. (A)

To stop a process in such a way that it can be resumed.

An APPC or CPI-C application that can be started, either by an operator or automatically by SNAP-IX, in response to a request from an invoking transaction program (TP). Contrast with invoking TP.

To start a command, procedure, or program.

An APPC or CPI-C application that is started, either by an operator or automatically by SNAP-IX, in response to a request from an invoking transaction program (TP). See also invokable TP and invoking TP.

An APPC or CPI-C application that issues a request, specifying the name of an invokable transaction program (TP), to start a conversation with that TP. Contrast with invokable TP and invoked TP.

J

A standard for coding character sets.

Java is an object-oriented programming language. Unlike other languages such as C, Java is compiled into Java byte codes, and not into native instructions for a specific computer or operating system. These byte codes are interpreted at run time by a piece of software known as the Java Virtual Machine.

SNAP-IX provides a CPI-C application programming interface (API) for use in Java applications (in addition to the standard C-language CPI-C API).

A unit of work defined by a user that is to be accomplished by a computer. Loosely, the term job is sometimes used to refer to a representation of a job. This representation may include a set of computer programs, files, and control statements to the operating system. (A)

A control language used to identify a job to an operating system and to describe the job's requirements.

An IBM licensed program that receives jobs into the system and processes all output data produced by the jobs.

In remote job entry (RJE), a file sent to the host that includes commands to be executed at the host and optionally includes data to be processed by the host.

A list of jobs waiting to be processed by the system.

K

A Japanese ideographic alphabet. In kanji, each character is represented by 2 bytes. See also katakana.

One of the two common Japanese phonetic alphabets (the other is hiragana). In katakana, each character is represented by 1 byte. Katakana is primarily used to write foreign words phonetically. See also kanji.

The part of an operating system that performs basic functions such as allocating hardware resources.

Synonym for system dump.

The state in which a process runs kernel code. Contrast with user mode.

An input device consisting of various keys that allows the user to input data, control cursor and pointer locations, and to control the dialog with the workstation.

A physical grouping of keys on a keyboard such as the numeric key pad and the cursor key pad.

An operating system command that stops a process.

For processor storage, real and virtual storage, and channel volume, 1024 bits.

For disk storage capacity and communications volume, 1000 bits.

For processor storage, real and virtual storage, and channel volume, 1024 bytes.

For disk storage capacity and communications volume, 1000 bytes.

L

An indicator, displayed on the 3270 status line, that shows the time it took for the host to respond the last time an AID key was pressed. See also host response time and response time monitor.

Synonym for nonswitched line.

A collection of functions, calls, subroutines, or other data.

The portion of a data circuit external to data circuit-terminating equipment (DCE), that connects the DCE to a data switching exchange (DSE), that connects a DCE to one or more other DCEs, or that connects a DSE to another DSE.

An ASCII character that causes an output device to move forward one line.

A printer that prints output, one line of characters at a time, as a unit. Output of line printers is in constant-width characters.

The rate at which data is transmitted from one point to another over a telecommunication line.

The number of binary digits that can be sent over a telecommunication line in one second, expressed in bits per second (bps).

In data communications, a transmission medium and data link control component that together transmit data between adjacent nodes.

In SNA, the combination of the link connection (the transmission medium) and two link stations, one at each end of the link connection. A link connection can be shared among multiple links in a multipoint or SATF configuration.

To interconnect items of data or portions of one or more computer programs: for example, the linking of object programs by a linkage editor, linking of data items by pointers.

In X.25 communications, the link level elements used for data interchange between a DCE and a DTE.

The role (primary, secondary, or negotiable) that the link station is configured to play on the current link. See also negotiable link station, primary station, and secondary station.

The hardware and software components within a node representing a connection to an adjacent node over a specific link. For example, if node A is the primary end of a multipoint line that connects to three adjacent nodes, node A will have three link stations representing the connections to the adjacent nodes.

A sequential log of events that occur on the link. This log can help determine the source of a recurring error.

A protocol for connection-oriented data transfer across a local area network (LAN). For example, used for transporting SNA data traffic over a Token Ring or Ethernet LAN.

A computer network located on a user's premises within a limited geographical area. Communication within a local area network is not subject to external regulations; however, communication across the LAN boundary may be subject to some form of regulation. See also wide area network.

In Transmission Control Protocol/Internet Protocol, the host on the network at which a particular operator is working.

In an internet, the host to which a user's terminal is connected without using the internet.

A method of logging SNAP-IX error and audit messages in files on each server. Contrast with central logging.

The logical unit that manages a session on a local node. See also logical unit, session, and local node.

A network point immediately accessible without use of a telecommunication line.

A dynamically assigned value used at a type 2.1 node to identify traffic for a particular session using a given transmission group (TG). The LFSID is encoded in the ODAI, OAF, and DAF fields of the transmission headers that accompany session messages exchanged over the TG.

The means by which integrity of data is ensured by preventing more than one user from accessing or changing the same data or object at the same time.

To record. For example, to record all messages on the system printer.

A list of messages, such as an error log.

A file used to store messages generated by SNAP-IX, which report events such as: failures of software, hardware, or links; damaged or missing files; connection statistics; configuration problems; and system status. This file can be viewed using a text editor. See also audit log and error log.

In X.25 packet mode operation, a sending channel and a receiving channel that together are used to send and receive data over a data link at the same time. Several logical channels can be established on the same data link by interleaving the transmission of packets.

A number that uniquely identifies a logical channel.

In a local area network, the protocol that governs the exchange of transmission frames between data stations independently of how the transmission medium is shared. The LLC protocol was developed by the IEEE 802 committee and is common to all LAN standards.

A type of network accessible unit that enables end users to communicate with each other and gain access to network resources.

In SNA, a port through which an end user accesses the SNA network in order to communicate with another user. An LU may be capable of supporting many sessions with other LUs.

An identifier, consisting of a fully qualified LU name, transaction instance number, and sequence number, that is used by a resource recovery manager to identify backout synchronization points. See also sequence number.

An LU that uses SNA Transmission Control and SNA Flow Control layers. Higher-layer protocols are end user and product-defined.

An application programming interface (API) that allows access to host applications using logical unit (LU) type 0. LU0 provides a simple and easy-to-use interface, but operates only with LU type 0 and does not provide access to the SSCP session. See also Conventional LU Application Programming Interface.

An SNA session that supports communication between an application and multiple input/output devices. This type of session is used for 3270 printing and remote job entry (RJE) functions.

An SNA session that uses a 3270 device data stream to support communication between an application and a display.

An SNA session that uses a 3270 device data stream to support communication between an application and a printer.

A type of logical unit that supports general communication between programs in a distributed processing environment. LU 6.2 is characterized by (a) a peer relationship between session partners, (b) efficient utilization of a session for multiple transactions, (c) comprehensive end-to-end error processing, and (d) a generic application programming interface (API) consisting of structured verbs that are mapped into a product implementation.

To begin a session at a display station.

To gain access to a computer system by entering identification and authentication information at the workstation.

A string of characters that uniquely identifies a user to the system.

The shell that is started when a user logs into the Solaris computer system. The login shell for a particular user is determined by the entry in the /etc/passwd file for that user. See also shell.

To end a session with a computer system at a display station.

Synonym for log in.

Synonym for log off.

A capability of nodes to attach directly to one another using basic peer-to-peer protocols to support multiple and parallel sessions between logical units.

A type 2.1 node that supports independent LU protocols but does not support CP-CP sessions. It may be a peripheral node attached to a boundary node in a subarea network, an end node attached to an APPN network node in an APPN network, or a peer-connected node directly attached to another LEN node or APPN end node. Contrast with APPN end node and APPN network node.

Least significant; rightmost. For example, the digit 9 in the number 526819.

In SNA, a session between two logical units (LUs) of the same type that supports communication between two end users, or between an end user and an LU services component.

A group of host LUs with common characteristics that enable only LUs in the group to be used interchangeably for a particular purpose.

A generic name for logical units (LUs) used by 3270 emulation, RJE, or LUA applications.

M

A unique address assigned to each Token Ring or Ethernet adapter card and used to identify a specific node on the local area network (LAN).

A label that is declared at the start of a program or file. The label can then be used to represent the values assigned to the label in the declaration.

A name or label used in place of a number of other names.

A large computer, particularly one to which other computers can be connected so that they can share facilities the mainframe provides. The term usually refers to hardware only and typically applies to an IBM System/370 computer.

The first program unit to receive control when a program is run.

A collection of objects that can be accessed by means of a network management protocol.

A definition for management information that specifies the information available from a host or gateway and the operations allowed.

One of the types of network services in control points (CPs) and physical units (PUs). Management services are the services provided to assist in the management of SNA networks, such as problem management, performance and accounting management, configuration management, and change management.

An LU 6.2 conversation type specified by the allocating transaction program. Transaction programs using a mapped conversation can exchange messages of arbitrary format regardless of the underlying data stream. System-defined or user-defined mappers can perform data transformation for the transaction programs. Contrast with basic conversation.

The server that holds the master copy of the SNAP-IX domain configuration. Changes to the running configuration must be made to the configuration file on this server; they are automatically copied to other servers on the LAN. See also backup server.

In local area networks, the sublayer of the data link control layer that supports medium-dependent functions and uses the services of the physical layer to provide services to the logical link control (LLC) sublayer. The MAC sublayer includes the method of determining when a device has access to the transmission medium.

For processor storage, real and virtual storage, and channel volume, 1,048,576 bits.

For disk storage capacity and communications volume, 1,000,000 bits.

For processor storage, real and virtual storage, and channel volume, 1,048,576 bytes.

For disk storage capacity and communications volume, 1,000,000 bytes.

A unit of measure of frequency. One megahertz equals 1,000,000 hertz.

All of the addressable storage space in a processing unit and other internal storages that is used to execute instructions.

The means by which the computer system records its state at the time of a failure.

A list of options displayed to the user by a data processing system, from which the user can select an action to be initiated.

A rectangular area at the top of the client area of a window that contains the titles of the standard pull-down menus for that application.

The name used by the initiator of a session to designate the characteristics desired for the session, such as traffic pacing values, message-length limits, sync point and cryptography options, and the class of service within the transport network.

A device that converts digital data from a computer to an analog signal that can be transmitted on a telecommunication line, and converts the analog signal received to digital data for the computer.

A device that connects a workstation directly to a computer port. When two devices both function as DTEs (data terminal equipment), the cable that connects them must transmit send and receive signals using a modem eliminator. For some protocols (for example, SDLC), the modem eliminator is an active device that generates signals such as clock signals. Similar to null modem.

In SNA, the name used by the initiator of a session to designate the characteristics desired for that session, such as traffic pacing values, message length limits, and the class of service within the transport network.

A graphical user interface that runs on the X Windows system. The SNAP-IX 3270 emulation program is available in two versions: a Motif version and a character-based version.

The SNAP-IX program that enables the user to configure and manage the SNAP-IX system by entering information and making choices in the windows of a Motif application.

A commonly used pointing device, containing one or more buttons, with which a user can interact with a product or the operating environment.

A link with more than two stations.

In SDLC, a means whereby one primary station can communicate with multiple secondary stations on the same line.

Contrast with point-to-point link.

A technique for transporting management services data between management services function sets over LU-LU and CP-CP sessions.

A general data stream (GDS) variable that contains routing, status, and error information for an APPN network.

More than one connection between two LU pairs over the same link.

Implies MVS/370, the MVS/XA product, and the MVS/ESA product.

Consists of MVS/System Product Version 1 and the MVS/370 Data Facility Product operating on a System/370 processor.

A type of operating system used on an IBM System/370 computer.

To interleave or simultaneously transmit two or more messages on a single channel.

A mode of operation that provides for concurrent performance or interleaved processing of two or more tasks.

A mode of operation that enables two or more users to use the services of a processor within a given period of time.

N

In SNA, a response indicating that a request did not arrive successfully or was not processed successfully by the receiver. Contrast with positive response.

A link station that can perform the role of either a primary station or a secondary station. During activation of the link, this link station and the remote link station determine which station will perform as primary and which will perform as secondary.

An IBM monitoring and reporting system that runs on a host computer and gathers data for administrative tasks such as operations management, problem determination, and performance management.

A configuration of data processing devices and software connected for information interchange.

A group of nodes and the links interconnecting them.

The SNAP-IX component on PC clients that handles communications with SNAP-IX servers across the local area network (LAN). The NAP must be running on a client before any other SNAP-IX programs can be used.

A logical unit (LU), physical unit (PU), control point (CP), or system services control point (SSCP). It is the origin or the destination of information transmitted by the path control network. Synonymous with network addressable unit. See also network address.

An identifier for a node, station, or unit of equipment in a network.

In a subarea network, an address, consisting of subarea and element fields, that identifies a link, link station, physical unit, logical unit, or system services control point. Subarea nodes use network addresses; peripheral nodes use local addresses or local-form session identifiers (LFSIDs). The boundary function in the subarea node to which a peripheral node is attached transforms local addresses or LFSIDs to network addresses and vice versa.

Synonym for network accessible unit.

An IBM licensed program that serves as a base for command processors that can monitor, control, and improve the operation of a network.

An IBM licensed program that provides communication controller support for single-domain, multiple domain, and interconnected network capability.

In TCP/IP, that part of the IP address that defines a network. The length of the network ID depends on the type of network class (A, B, or C).

A 1- to 8-byte customer-selected name or an 8-byte IBM-registered name that uniquely identifies a specific subnetwork.

In MPTN architecture, the address qualifier of a transport provider address that identifies a group of nodes according to the network in which they reside.

The process of planning, organizing, and controlling a communication-oriented data processing or information system.

A management services request/response unit (RU) that flows over an active session between control point management services and physical unit management services (SSCP-PU session).

The symbolic identifier by which users refer to a network accessible unit, a link, or a link station within a given subnetwork. In APPN networks, network names are also used for routing purposes. Contrast with network address.

See APPN network node.

An APPN network node that provides network services for its local LUs and client end nodes.

In X.25 communications, the organization, often a PTT, that provides a public network.

In X.25 communications, the X.121 address containing up to 15 binary code digits.

A control character that causes the print or display position to move down one line. Usually a carriage return is implicitly associated with an NL.

An endpoint of a link or a junction common to two or more links in a network. Nodes can be processors, communication controllers, cluster controllers, or terminals. Nodes can vary in routing and other functional capabilities.

The SNAP-IX configuration file that contains the configuration of a node and its associated resources. Contrast with domain configuration file.

A unique string of characters that identifies the node on a network.

The SNAP-IX application programming interface (API) that enables applications to configure and manage SNAP-IX resources.

A resource that provides the communications capabilities of a particular node and is configured in the node configuration file. The following are types of node resources:

• Connectivity resources (data link controls, ports, link stations, and connection networks)

• Logical units

• Modes and classes of service

• Directory information

Contrast with domain resource.

A designation of a node according to the protocols it supports or the role it plays in a network. Node type was originally denoted numerically (as 1, 2.0, 2.1, 4, and 5) but is now characterized more specifically by protocol type (APPN network node, LEN node, subarea node, and interchange node, for example) because type 2.1 nodes and type 5 nodes support multiple protocol types and roles.

An additional level of security beyond that provided by the network addressing scheme. Node verification helps to ensure that a connection reaches the correct remote station. It is available on LU 6.2 connections only. See also BIND password and session-level security .

A disturbance that affects a signal and potentially distorts the information carried by that signal.

A way of requesting a service over an interface so that if the request cannot be completed immediately, the requesting process is able to continue and is not suspended.

Contrast with blocking mode. See also asynchronous completion.

Data traffic on the media that is only made up of repetitive control information and does not contain end user data.

An invokable transaction program (TP) that is loaded automatically every time an incoming request to start a conversation arrives at the local logical unit (LU) after having been issued by an invoking TP.

A binary code system in which a signal condition must be sustained for the full time interval and does not revert to a standby or quiescent state between signal elements.

An alternative binary code system to NRZ.

A telecommunication line on which connections do not have to be established by dialing.

Synonymous with leased line. Contrast with switched line.

In the C language, a pointer guaranteed not to point to a data object.

A simplified form of modem elimination that is passive and cannot itself generate clock signals.

Having a zero byte at the end. In the C language, character strings are stored this way.

O

The bottom line on a 3270 or 5250 session window that displays information about the status of that display session.

A term used in HLLAPI for the status line on an IBM display terminal.

An invokable transaction program (TP) that is manually started by an operator.

Software that controls the execution of programs and that may provide services such as resource allocation, scheduling, input/output control, and data management.

In SNA, a field in a FID0 or FID1 transmission header that contains the address of the originating network accessible unit (NAU). Contrast with destination address field (DAF).

In X.25 communications, a call being made to another data terminal equipment (DTE).

The user who has the highest level of access authority to a data object or action, as defined by the object or action; usually the creator of the object.

P

A technique used by a receiving component to control the rate of transmission by sending a component to prevent overrun or congestion.

In SNA, an indicator that signifies the readiness of a receiving component to accept another pacing group. The indicator is carried in a response header (RH) for session-level pacing.

In data communications, a sequence of binary digits, including data and control signals, that is transmitted and switched as a composite whole.

In X.25 communications, control information at the start of the packet; the contents of the packet depend on the packet type.

The packet format and control procedures for exchange of packets containing control information and user data between data terminal equipment (DTE) and data circuit-terminating equipment (DCE).

A part of Recommendation X.25 that defines the protocol for establishing logical connections between two DTEs and for transferring data on these connections.

In X.25 packet mode operation, the level of the interface between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) associated with the exchange of data and signals contained in packets.

Synonym for packet switching.

In X.25 communications, the length of the user data in a data packet.

Routing and transferring data by addressing packets so that a channel is occupied only during packet transmission. On completion of the transmission, the channel is available for transfer of other packets. Synonymous with packet mode operation.

To fill unused positions in a field with dummy data, usually zeros or blanks.

Bytes inserted in the data stream to maintain alignment of the protocol requests on natural boundaries. Padding increases the ease of portability to some machine architectures.

A block of instructions, data, or both.

The number of lines that can fit into a window.

In a virtual storage system, a fixed-length block that has a virtual address and is transferred as a unit between real storage and auxiliary storage. (A)

The condition in which multiple tasks are being performed simultaneously within the same activity.

In SNA, two or more concurrently active sessions between the same two network accessible units (NAUs) using different pairs of network addresses or local-form session identifiers. Each session may have independent session parameters.

A process that has spawned a child process using the fork primitive.

Pertaining to a secured resource, either a file or library, whose user list is shared with one or more files or libraries. Contrast with child.

The directory one level above the current directory.

In data communications, the remote application program or the remote computer.

In SNA, the remote participant in a session. See also logical unit and session.

A value used in authentication or a value used to establish membership in a set of people having specific privileges.

A unique string of characters known to a computer system and to a user, who must specify the character string to gain access to a system and to the information stored within it.

In computer security, a string of characters known only to the user and the system. The user must specify it to gain access to a system and the data stored with it.

The process of requiring a user to enter a password in order to log on to a system.

In a network, any route between any two nodes.

The route used to locate files; the storage location of a file. A fully qualified path lists the drive identifier, directory name, subdirectory name (if any), and file name with the associated extension.

Synonym for transport network.

In SNA, a message unit consisting of a transmission header (TH) alone, or a TH followed by a basic information unit (BIU) or a BIU segment.

A file name specifying all directories leading to the file. See relative path name.

A network made up of connections between type 6.2 LUs.

In SNA, a system containing a type 2.1 physical unit supporting type 6.2 independent LUs. Peer systems cooperatively establish LU-LU sessions without the services of a SNA host.

Pertaining to data communications between two nodes that have equal status in the interchange. Either node can begin the conversation. See also Logical Unit Type 6.2.

In remote job entry (RJE), a data record sent by the host to indicate how the data that follows the PDIR is to be processed.

In SNA, a node that uses local addresses for routing and therefore is not affected by changes in network addresses. A peripheral node requires boundary-function assistance from an adjacent subarea node. A peripheral node can be a type 1, 2.0, or 2.1 node connected to a subarea boundary node.

In X.25 and frame-relay communications, a virtual circuit that has a logical channel permanently assigned to it at each data terminal equipment (DTE). Call-establishment protocols are not required. Contrast with switched virtual circuit.

Codes that determine how the file can be used by any users who work on the system.

The component that manages and monitors the resources (such as attached links and adjacent link stations) associated with a node, as requested by an SSCP via an SSCP-PU session. An SSCP activates a session with the physical unit in order to indirectly manage, through the PU, resources of the node such as attached links. This term applies to type 2.0, type 4, and type 5 nodes only.

In SNA, a component that provides a subset of system services control point (SSCP) functions for activating the physical unit (PU) within its node and its local link resources. Each type 1, type 2, and type 4 node contains a PUCP; a type 5 node contains an SSCP.

To direct the data so that the output from one process becomes the input to another process. The standard output of one command can be connected to the standard input of another with the pipe operator ( | ). Two commands connected in this way constitute a pipeline.

A one-way communication path between a sending process and a receiving process.

An identifier that indicates the location of an item of data. (A)

A switched or nonswitched link that connects a single remote link station to a node or to another station. Contrast with multidrop link.

In data communications, an interrogation that determines whether a station is ready to transmit information.

An access point for data entry or exit.

A connector on a device to which cables for other devices such as display stations and printers are attached.

The representation of a physical connection to the link hardware. A port is sometimes referred to as an adapter; however, there can be more than one port on an adapter. There may be one or more ports controlled by a single DLC process.

An abstraction used by transport protocols to distinguish among multiple destinations within a host machine.

In the Internet suite of protocols, a 16-bit number used to communicate between TCP or UDP and a higher-level protocol or application. Some protocols, such as File Transfer Protocol (FTP) and Simple Mail Transfer Protocol (SMTP), use the same well-known port number in all TCP/IP implementations.

An IEEE standard for computer operating systems.

A response that indicates a message was received successfully.

In SNA, a response indicating that a request arrived and was successfully received and processed. Contrast with negative response. See also definite response.

A computer program that effects some final computation on a datastream.

A computer program that effects some preliminary computation on a datastream.

A conceptual two-dimensional surface in storage on which data for a portion of the display surface is represented.

In SNA, the logical unit (LU) that contains the primary half-session for a particular LU-LU session and thus sends the BIND to activate a session with its partner LU. Contrast with secondary logical unit. See also logical unit.

In SNA, the station on a data link that is responsible for control of the data link. There can be only one primary station on a data link. All traffic over the data link is between the primary station and a secondary station. Specific responsibilities assigned to the primary station include initialization of control signal interchange, organization of data flow, and actions to perform error control and error recovery functions.

Contrast with secondary station.

A file containing a list of the names of files waiting to be printed.

A program (such as lp on Solaris) to which printer output can be directed instead of sending it directly to the printer. The spooler manages the printing process, enabling control to be returned to the process that generated the print request without waiting for printing to be completed.

A device externally attached to the system unit, used to print system output on paper.

A rank assigned to a task that determines its precedence in receiving system resources, the CPU in particular.

The relative significance of one job to other jobs in competing for allocation of resources.

A user logged on to an account with root user authority.

An activity within the system that is started by a command, a shell program, or another process. When a program is running, it is called a process.

Each process in the system is a member of a process group that is identified by a process group ID. This grouping permits the signalling of related groups of processes. A newly created process joins the process group of its creator.

A unique number assigned to a process by the operating system. The number is used internally by processes to communicate.

A sequence of instructions suitable for processing by a computer. Processing may include the use of an assembler, a compiler, an interpreter, or a translator to prepare the program for execution, as well as to execute it.

To design, write, and test computer programs. (A)

The initial parameter values passed to a target program as input or used to set up the process environment.

A displayed field in which a user cannot enter, modify, or erase data.

A set of semantic and syntactic rules that determine the behavior of functional units in achieving communication.

In SNA, the meaning of, and the sequencing rules for, requests and responses used for managing a network, transferring data, and synchronizing the states of network components.

A feature that supports the establishment and use of dependent LU sessions between host computers and downstream PUs through an SNA node. This feature removes the need for a separate connection between the host and each downstream LU.

A device associated with a remote job entry (RJE) workstation that handles unformatted output data from the host.

Q

An X.25 protocol that allows the transfer of data link control information between two adjoining SNA nodes that are connected through an X.25 packet-switching data network. The QLLC provides the qualifier 'Q' bit in X.25 data packets to identify packets that carry logical link protocol information.

A name made unique by the addition of one or more qualifiers.

A modifier that makes a name unique.

An optional CCITT-specified facility that provides a function similar to the SNA class of service. See also class of service.

An invokable transaction program (TP) that can be started by only one incoming conversation request at a time. Incoming conversation requests that arrive while the queued TP is running do not start the TP again. The incoming requests are queued until the TP finishes execution and is restarted or, for an APPC TP, until the TP issues another RECEIVE_ALLOCATE verb. Contrast with nonqueued TP.

R

The processing used by the endpoints of an RTP connection for route setup, nondisruptive route switching, adaptive-route-based congestion control, and error recovery. This protocol is used in High-Performance Routing (HPR).

In High-Performance Routing (HPR), the connection established between the endpoints of the route to transport session traffic.

In SNA, the pacing of message units that a component is receiving. See pacing. Contrast with send pacing.

In data communications, a condition that occurs when no data is received in a given period of time.

A class of computer designs that uses a relatively small, simplified set of frequently used instructions for rapid execution.

A set of characters, meta characters, and operators that define a string or group of strings in a search pattern.

The name of a directory or file expressed as a sequence of directories followed by a file name, beginning from the current directory. Relative path names do not begin with a / (slash) but are relative to the current directory.

Pertaining to a system, program, or device that is accessed through a telecommunication line.

A feature of SNAP-IX that enables an operator at the host NetView program to issue SNAP-IX administration commands (see SPCF) or Solaris operating system commands (see UCF) on the SNAP-IX computer.

Any host on the network except the one at which a particular operator is working.

Submission of a job through an input unit that has access to a computer through a data link.

Initiating a session on a system that is accessed through a communications line.

A node other than the local node to which physical and logical connections can be established.

Issuing print jobs to one machine (client) to print on another machine (server) on a network.

A system that is connected to your system through a communication line.

In SNA, a message unit that signals initiation of an action or protocol. Synonym for request unit.

Control information associated with a particular request/response unit (RU). The RH precedes the RU and specifies its type (request unit or response unit).

A signal activated on an SDLC link prior to a transmission, to indicate readiness to send data.

In SNA, a message unit that contains control information such as a request code, or function management (FM) headers, end-user data, or both. Synonymous with request.

The interface implemented by the SNAP-IX Conventional LU Application Programming Interface (LUA) that enables applications to send and receive data in the form of SNA request units and response units.

In SNA, a generic term for a request unit or a response unit.

In SNA, a message unit that acknowledges receipt of a request; a response consists of a response header (RH), a response unit (RU), or both.

The elapsed time between the end of an inquiry or demand on a computer system and the beginning of the response; for example, the length of time between an indication of the end of an inquiry and the display of the first character of the response at a user terminal. (A)

For response time monitoring, the time from the activation of a transaction until a response is received, according to the response time definition coded in the performance class.

A 3270 and NetView facility that monitors the amount of time it takes for a host to respond during 3270 display sessions. See also host response time and Last Transaction Time Indicator.

A message unit that acknowledges a request unit. It may contain prefix information received in a request unit. If positive, the response unit may contain additional information such as session parameters in response to a BIND session. If negative, it contains sense data defining the exception condition.

A value that is returned to a program to indicate the results of an operation requested by that program.

The value returned by a function.

A facility that enables a data terminal equipment (DTE) to receive incoming packets that request reverse charging.

The user name for the system user with the most authority.

The directory ( / ) that contains all other directories in the system.

The basic Solaris file system, onto which all other file systems can be mounted. The root file system contains the operating system files that get the rest of the system running.

An ordered sequence of nodes and transmission groups (TGs) that represent a path from an origin node to a destination node traversed by the traffic exchanged between them.

The path that network traffic uses to get from source to destination.

A subcomponent of the topology and routing services component of APPN that determines the preferred route between a specified pair of nodes for a given class of service.

A computer that determines the path of network traffic flow. The path selection is made from several paths based on information obtained from specific protocols, algorithms that attempt to identify the shortest or best path, and other criteria such as metrics or protocol-specific destination addresses.

An attaching device that connects two LAN segments, which use similar or different architectures, at the reference model network layer.

In TCP/IP, synonymous with gateway.

Contrast with bridge.

The process of determining the path to be used for transmission of a message over a network.

The assignment of the path by which a message is to reach its destination.

In SNA, the forwarding of a message unit along a particular path through a network as determined by parameters carried in the message unit, such as the destination network address in a transmission header.

S

To move a display image vertically or horizontally to view data that otherwise cannot be observed within the boundaries of the display screen.

A window component that shows a user that more information is available in a particular direction and can be scrolled into view. Scroll bars can be either horizontal or vertical.

In SNA, the logical unit (LU) that contains the secondary half-session for a particular LU-LU session. It receives BIND requests from a primary LU. Contrast with primary logical unit.

In SNA, a station on a link that operates under the control of a primary station. Contrast with primary station.

In SNA, an optional function of path control that divides a basic information unit (BIU) received from transmission control into two or more path information units (PIUs). The first PIU contains the request header (RH) of the BIU and usually part of the RU. The remaining PIU or PIUs contain the remaining parts of the RU. When segmenting is not done, a PIU contains a complete BIU.

Entity used to control access to system resources. Processes can be locked to a resource with semaphores if the processes follow certain programming conventions.

In SNA, the pacing of message units that a component is sending. Contrast with receive pacing.

A value sent or received, or a negative response to indicate what error occurred.

In communications, a number assigned to a particular frame or packet to control the transmission flow and receipt of data.

A functional unit that provides shared services to workstations over a network; for example, a file server, a print server, a mail server.

A SNAP-IX server is an SNA node and provides SNA communications functions to clients.

A logical address that allows a system to route data between a remote device and the appropriate communications support.

A SNAP-IX facility that enables a NetView user to issue administration commands from the NetView console to manage a SNAP-IX system.

A program that provides a function internal to SNAP-IX.

A transaction program implemented by a transaction processing system. Service transaction programs perform such functions as providing access to remote data bases and remote queues. Contrast with application transaction program. See transaction program.

In SNA, a logical connection between two network accessible units (NAUs) that can be activated, tailored to provide various protocols, and deactivated, as requested. Each session is uniquely identified in a transmission header (TH) accompanying any transmissions exchanged during the session.

In SNA, (a) one of the components of transmission control. Session control is used to purge data flowing in a session after an unrecoverable error occurs, resynchronize the data flow after such an error, and perform cryptographic verification; and (b) an RU category used for requests and responses exchanged between the session control components of a session and for session activation/deactivation requests and responses.

A session-layer component in an APPN network node or in a subarea node boundary or gateway function that connects two stages of a session. Session connectors swap addresses from one address space to another for session-level intermediate routing, segment session message units as needed, and (except for gateway function session connectors) adaptively pace the session traffic in each direction. See also half-session.

In SNA, a flow control technique in which a receiving half-session or session connector controls the data transfer rate (the rate at which it receives request units on the normal flow). It is used to prevent overloading a receiver with unprocessed requests, when the sender can generate requests faster than the receiver can process them.

For logical unit (LU) 6.2, partner LU verification and session cryptography. See BIND password and node verification .

The maximum number of concurrently active LU-LU sessions that a particular logical unit (LU) can support.

A transmission facility, such as Ethernet, FDDI, or token ring, on which multiple pairs of nodes can form concurrently active links.

A software interface between a user and the operating system of a computer. Shell programs interpret commands and user interactions on devices such as keyboards, pointing devices, and touch-sensitive screens and communicate them to the operating system. Shells simplify user interactions by eliminating the user's concern with operating system requirements. A computer may have several layers of shells for various levels of user interaction.

The character string on the command line indicating that the system can accept a command (typically the $ character).

In the Solaris operating system, a series of commands, combined in a file, that carry out a particular function when the file is run.

Facilities of the shell program for assigning variable values to constant names.

An encoding scheme consisting of single bytes and double bytes used for character encoding. Because of the large number of characters in the Japanese and other Asian languages, the 8-bit byte is not sufficient for character encoding.

In CPI-C, predefined information about a conversation, stored in a side information profile. Side information provides initial values for the partner LU name, mode name, and TP name conversation characteristics. The use of side information is optional.

A simple method of communication between two processes. One process can inform the other process when an event occurs.

In operating system operations, a method of interprocess communication that simulates software interrupts.

A subroutine called when a signal occurs.

In the Internet suite of protocols, a network management protocol that is used to monitor routers and attached networks. SNMP is an application layer protocol. Information on devices managed is defined and stored in the application's Management Information Base (MIB).

In SNA, a character string composed of EBCDIC controls, optionally intermixed with end-user data, that is carried within a request/response unit.

A type 5 node, which contains an SSCP.

The part of a user-application network that conforms to the formats and protocols of Systems Network Architecture. It enables reliable transfer of data among end users and provides protocols for controlling the resources of various network configurations. The SNA network consists of network accessible units (NAUs), boundary function, gateway function, and intermediate session routing function components; and the transport network.

A unique host identifier created by the concatenation of a port identifier with a TCP/IP address.

A port on a specific host; a communications end point that is accessible through a protocol family's addressing mechanism. A socket is identified by a socket address.

An implementation of the UNIX operating system for Intel and SPARC processors, developed by Sun Microsystems, Inc. SNAP-IX is one product that runs on the Solaris operating system.

The input to a compiler or assembler, written in a source language.

Synonym for invoking program.

In remote job entry (RJE), a queue of jobs submitted by users of a particular RJE workstation. The jobs are held on the spool until the workstation can send them to the host for processing.

A program that intercepts data going to a device driver and writes it to a disk. The data is later printed or plotted when the required device is available. A spooler prevents output from different sources from being intermixed.

A disk file containing output that has been saved for later printing.

Files used in the transmission of data among devices.

In SNA, a session between a system services control point (SSCP) and a logical unit (LU). The session enables the LU to request the SSCP to help initiate LU-LU sessions.

In SNA, a session between a system services control point (SSCP) and a physical unit (PU); SSCP-PU sessions allow SSCPs to send requests to and receive status information from individual nodes in order to control the network configuration.

An area in storage that stores temporary register information and return addresses of subroutines.

A list constructed and maintained so that the next data element to be retrieved is the most recently stored.

The calling sequence that indicates the path taken by a process to get to its current location.

A workstation that can perform tasks without being connected to other resources such as servers or host systems.

The place where many programs place error messages.

The primary source of data going into a command. Standard input comes from the keyboard unless redirection or piping is used, in which case standard input can be from a file or the output from another command.

The primary destination of data coming from a command. Standard output goes to the display unless redirection or piping is used, in which case standard output can go to a file or another command.

A computer or device that can send or receive data.

An input or output point of a system that uses telecommunication facilities, such as one or more systems, computers, workstations, devices, and associated programs at a particular location that can send or receive data over a telecommunication line.

A location on a device at which an operation is performed.

In SNA, a link station.

The bottom line on a 3270 emulation display, which is reserved for system messages and information about the current 3270 session. HLLAPI refers to the status line as the Operator Information Area (OIA).

The bottom line on the remote job entry (RJE) console program display, which shows the current state of the RJE workstation's communications with the host.

A means of encoding variable-length data, or data that is not intended for 3270 display, for transmission in a 3270 data stream.

The file that holds information about a user's 3270 customization. The name of this file must have the extension .stu.

The file that holds information about the customization of a remote job entry (RJE) workstation. The name of this file must have the extension .sty.

Interconnected subareas, their directly attached peripheral nodes, and the transmission groups that connect them. Contrast with APPN network .

A node that uses network addresses for routing and maintains routing tables that reflect the configuration of the network. Subarea nodes can provide gateway function to connect multiple subarea networks, intermediate routing function, and boundary function support for peripheral nodes. Type 4 and type 5 nodes can be subarea nodes.

A telecommunication line in which the connection is established by dialing. Contrast with nonswitched line.

An X.25 circuit that is dynamically established when needed. The X.25 equivalent of a switched line. Contrast with permanent virtual circuit (PVC).

A name used during conversation initialization by a CPI-C application to identify a particular set of side information parameters in the SNAP-IX configuration file. This set of side information parameters includes the partner application's transaction program (TP) name and LU name, the mode used for communications, and any security information required by the partner application.

The component of the node that implements two-phase commit and resynchronization processing. The subcomponents of the SPM are sync point services (SPS) and the protection managers (the conversation resource protection managers and the local resource protection managers).

A synchronization processing level, specified during allocation of a conversation, that enables distributed transaction programs to synchronize their resources at user-specified points, called synchronization points. Contrast with confirmation processing.

The component of the sync point manager that is responsible for coordinating the managers of protected resources during sync point processing. SPS coordinates two-phase commit protocols, resync protocols, and logging.