tab. To move a cursor to a preset location on a display screen.
tab group. In AIXwindows, a means of organizing XmPrimitive widgets into groups for more efficient traversal within and between groups.
table. An array of data in which each item can be unambiguously located by means of one or more values.
tablet. A special flat surface with a mechanism for indicating positions on it. A tablet is normally used as a locator.
tablet origin. A point on a tablet to which all other locations on the tablet correspond. The origin is either the lower-left corner or the center of the tablet.
tabulating window. In Performance Toolbox, a special form of window that tabulates the values of an instrument as data is received and can also calculate a line with a weighted average for each value.
tag. (1.) In GL, a marker in the display list used as a location for display list editing. (2.) In Interleaf, the alphanumeric name of an autonumber reference. This name can be assigned by Interleaf or by the writer; but it must match the autonumber of the component it is referencing.
tag field. In Pascal, the field of a record that defines the structure of the variant part. See also variant part.
tag-in. A control line bus that passes signals from the control unit to the host on the System 360/370 Parallel Channel Interface.
tag-out. A control line bus that passes signals from the host to the control unit on the System 360/370 Parallel Channel Interface.
Tagged Input Format File (TIFF). A graphics file format using bitmaps.
tape drive. A mechanism for moving magnetic tape and controlling its movement.
target. (1.) A system, a program within a system, or a device that interprets, rejects, or satisfies, and replies to requests received from a source. Contrast with source. (2.) The node at which a password is to be installed. If the password specifies a single nodelocked license, the target is the node licensed to run the product. If the password specifies multiple nodelocked licenses (that is, a compound password for nodelocked licenses), or licenses of any other type, then the target is a node running the license server daemon. (3.) For NIM, the client you are installing.
target file. A file created by the make program that contains a completed program.
target object. (Or receiver.) In SOM, the object responding to a method call. The target object is always the first formal parameter of a method procedure. For SOM's C-language bindings, the target object is the first argument provided to the method invocation macro, _methodName.
target program. Synonym for object program.
task. (1.) A basic unit of work to be performed. Some examples include a user task, a server task, and a processor task. (2.) A process and the procedures that run the process. (3.) In a multiprogramming or multiprocessing environment, one or more sequences of instructions treated by a control program as an element of work to be accomplished by a computer. (4.) In Ada language, a task operates in parallel with other parts of the program. It is written as a task specification (which specifies the name of the task and the names and formal parameters of its entries), and a task body which defines its execution. A task unit is one of the kinds of program unit. A task type is a type that permits the subsequent declaration of any number of similar tasks of the type. A value of a task type is said to designate a task. (5.) A C++ task is a lightweight, nonpreemptive routine that you can use to simulate the operation of programs. Tasks are nonpreemptive because only a single task is executing at any one time. Tasks are lightweight because less time and space are required to create a task than a true operating-system process.
task ID. In Ada language, analphabetic label or identification for a task. This label is determined by the debugger TASKS option. A task ID is assigned to each task that has not terminated.
Task Library. A C++ class library that provides the facilities to write programs that are made up of tasks.
tasking. Synonym for multitasking.
tbl. A preprocessor that formats tables for the nroff and troff commands.
TCB. See trusted computing base.
TCP. See Transmission Control Protocol.
TCP/IP. See Transmission Control Protocol/Internet Protocol.
TCW. Translation control word.
TD. Transmit Data used with EIA-232 Protocol.
telecommunication. The transmission of control signals and information between computer systems at two or more locations over telecommunication lines, or between a computer system and remote devices.
teleprocessing. Processing data that is received from or transmitted to a remote location by way of communication channels.
Telnet. In TCP/IP, the protocol that opens the connection to the system.
template. (1.) A representation of a keyboard that includes functions not engraved on the keyboard. (2.) Each command line stored in the buffer. (3.) In enhanced edit mode, a special character buffer associated with the terminal. (4.) In Mailer, an ASCII file you can create for conveniently including frequently typed information, such as your name and electronic mail address, in your mail messages. (5.) A family of C++ classes or functions with variable types.
template class. A C++ class instance generated by a class template.
template function. A C++ function generated by a function template.
temporary error. An error that requires an operation to be retried a number of times before it is successfully completed.
temporary scalar. In a source-level optimization, a scalar that is used to temporarily hold the contents of an array element or the result of a computation to eliminate logically redundant stores and loads of that element or result.
term. An expression that is a subportion of another expression, usually composed of other subportions by means of addition or subtraction.
terminal. (1.) A device, usually equipped with a keyboard and a display device, capable of sending and receiving information over a communications line. See also workstation. (2.) In a system or communications network, a point at which data can either enter or leave. (3.) In curses and extended curses, a special screen that represents what the workstation's display screen currently looks like. The terminal screen is identified by a window named curscr, which the user does not access directly. Instead, users make changes to the stdscr window (or a user-defined screen) and then the refresh (or wrefresh) window to update the terminal.
Terminal. In CDE, in the Front Panel, an item in the Personal Applications subpanel used to open a terminal window.
terminal application. An application running at a workstation (terminal).
terminal descriptor. In ODM, a named variable of type short, long, binary, char, or vchar used to define the basic data types in an ODM object class definition. See also short, long, binary, char, vchar, and object class.
terminal emulator. A program that allows a device such as a microcomputer or personal computer to enter and receive data from a computer system as if it were a particular type of attached terminal.
terminal mapping. To translate between a standard character set and a terminal-specific character set.
terminal screen. Synonym for display screen.
terminator. The part of the program product that performs the action necessary to end a job or program.
test mode. Mode employed in testing a new user interface, in which the compiled application is used to drive the interface. Allows building, modifying, testing, and refining operations without having to compile, link, and debug.
text. (1.) A type of data consisting of a set of linguistic characters (letters, numbers, and symbols) and formatting controls. (2.) The portion of a program that is able to be run. (3.) In kernel mode, contains kernel program code that runs. It is read only by a user process. (4.) In ASCII and data communications, a sequence of characters treated as an entity when preceded by one start-of-text and ended by one end-of-text communication control character. See also program text. (5.) In word processing, information intended for human viewing that is presented in a two-dimensional form, such as data printed on paper or displayed on a screen. (6.) The part of a message that is not the header or control information.
text buffer. A text storage area.
text cursor. A cursor that indicates where to type a character. The text cursor is controlled by the keyboard.
Text Editor. In CDE, the software application used to create and edit documents.
text field. In CDE, a rectangular area in a window where information is typed. Text fields with keyboard focus have a blinking text insertion cursor.
text formatting program. A program that determines the manner in which data will be placed on a page.
text indicators. Symbols at the bottom of the INed window to show directions the user can scroll to view additional portions of the file.
text input mode. Mode in which typed characters are interpreted by an editor as text entered into a file. See also command mode, and last line mode.
text lock. Allows the calling process to lock or unlock its text segments into memory.
text string. A sequence of characters (alphanumeric or special) defined by the user.
text widget. A text editor for customizing user interfaces and programmatic interfaces.
text wrap. See word wrap.
textport. In GL, a region on the display screen used to present textual output from graphical or nongraphical programs.
texture. A pattern used to fill rectangles, convex polygons, arcs, and circles.
tftp. See Trivial File Transfer Protocol.
thermal output. The heating load that a computer system places on the cooling system of the building, measured in British Thermal Units (BTU).
this. A C++ keyword that identifies a special type of pointer that references the class object in a member function.
thrashing. A condition, caused by a high level of memory over-commitment, in which the system is spending all of its time writing out virtual-memory pages and reading them back in. The application programs make no progress because their pages don't stay in memory long enough to be used. Memory load control is intended to avoid or stop thrashing.
thread. The dispatchable entity in AIX Version 4. Each thread represents the current execution state of a single instance of a program. Each user thread runs in the environment provided by a specific process, but multiple threads may share the resources owned by that process.
thread-serial service. A reentrant system service is thread-serial if it blocks the current thread and all other threads that attempt to call the same service or other related services until the first call returns.
thread-synchronous service. A reentrant system service is thread-synchronous if it blocks only the current thread and allows other threads to execute the same operation during the block.
threaded application. An application that performs its function by simultaneously using multiple execution paths (threads of control) within a single address space.
threshold. (1.) A logic operator with the property that if P is a statement, Q is a statement, R is a statement, and so on, then the threshold of P, Q, R, and so on, is true if at least N statements are true, and false if less than N statements are true. N is a specified nonnegative integer called the threshold condition. (2.) In computer graphics, a level above which all gray-scale image data can be represented as white and below which all gray-scale image data can be represented as black.
throughput. The number of workload operations that can be accomplished per unit of time.
throughput-class negotiation. In X.25 communications, an optional facility that allows a DTE to negotiate the speed at which its packets travel through the packet switching network.
throw expression. An argument to the exception being thrown.
ticket. An application-transparent mechanism that transmits the identity of an initiating principal to its target. A simple ticket contains the principal's identity, a session key, a timestamp, and other information, sealed using the target's secret key. A privilege ticket contains the same information as a simple ticket, and also includes a privilege attribute certificate. A ticket-granting ticket is a ticket to the ticket-granting service; a service ticket is a ticket for a specified service other than the ticket-granting service.
TIDL. Transactional Interface Definition Language.
tie-down resistor. A resistor used to hold the input to a logic function or gate to the low level. One end of the resistor is connected to ground or the appropriate negative voltage.
tie-up resistor. A resistor used to hold the input to a logic function or gate to the high level. One end of the resistor is connected to the appropriate positive voltage.
TIFF. See Tagged Input Format File.
tile. (1.) A pixmap. (2.) To fill a region with a pixmap. (3.) To replicate a pixmap in two dimensions.
time slice. The interval between scheduled checks by the CPU scheduler to see if a different thread should be dispatched. Unscheduled checks may occur as a result of interrupts or system calls.
time stamp. (1.) A time value expressed in milliseconds, typically since the last server reset. Time-stamp values wrap around usually after 49.7 days. The server, once given its current time, is represented by timestamp T and always interprets time stamps from clients by treating half of the time-stamp space as being earlier in time than T, and half the time-stamp space as being later in time than T. One timestamp value, represented by the constant CurrentTime, is never generated by the server. This value is reserved for use in requests to represent the current server time. (2.) Information added to a record or other form of data that shows the date and time at which a computer processed that record or data. (3.) An integer that describes the date and time at which a set of licenses was created. (4.) Records the date and time when an Ada-language compilation unit was last modified.
TIMED. Timed Server Protocol. A protocol used to synchronize a host's time with the time of other hosts.
timeslicing. A mechanism by which running threads are preempted at fixed intervals. This ensures that every thread is allowed time to execute.
timing loop. A loop placed around code whose performance is to be timed, such that the timing loop increases the number of executions of the code within it to a time that can provide a meaningful performance measurement.
title bar. The bar that appears across the top of a window and that contains a file name or title. It can be used for moving or activating the window.
TLB. See translation lookaside buffer.
TLB miss. A memory delay that occurs when a memory location is referenced and the page that contains that memory location does not have an entry in the appropriate transition lookaside buffer (instruction or data).
TLI. Transport Layer Interface.
toggle. (1.) A switching device such as a toggle key on a keyboard. (2.) Pertaining to any device having two stable states. (3.) To switch between two modes on a computer or network.
toggle button. In AIXwindows and Enhanced X-Windows, a graphical object that simulates a real-world toggle switch; it switches sequentially from one optional state to another.
token. (1.) The smallest independent unit of meaning of a program as defined by either the parser or the lexical analyzer. A token can contain data, a language keyword, an identifier, or other parts of a language syntax. (2.) In the m4 command, any string of letters and digits that the m4 command recognizes. (3.) A type of macro that the typesetting preprocessor replaces with an assigned string value. See also string register. (4.) In a local area network, the symbol of authority passed among data stations to indicate the station temporarily in control of the transmission medium.
token numbers. Nonnegative integers that represent the names of tokens.
token ring. A type of local area network that was developed under the auspices of the IEEE 802.5 Subcommittee. A token access procedure used with a sequential (ring) topology.
Toolkit. In AIXwindows and Enhanced X-Windows, a collection of C language data structures and subroutines that collectively expedite the development of graphical user interfaces for compatible applications written in C language.
top-down. An approach to problem solving that starts at the highest level of abstraction and proceeds toward the lowest level.
top-level. In AIXwindows and Enhanced X-Windows, pertaining to the widget classes at the top level of a widget-gadget hierarchy.
top-level transaction. A transaction that does not execute within the scope of another transaction. In other words, a top-level transaction is the root of a transaction family, even if it is the only transaction in the family tree.
top-level widget. In AIXwindows and Enhanced X-Windows, widget classes that are at or near the top level of the object class hierarchy, which is known as the Core class.
top-level window. In AIXwindows and Enhanced X-Windows, the main window that contains all other windows associated with a client application.
top shadow. In AIXwindows, an arrow band of lighter color across the top of a rectangular graphical object (a widget or gadget) that creates a three-dimensional appearance when the object is manipulated.
topic tree. In CDE, in a general help dialog box, an expandable and contractible list of topics that can be selected to display help information.
topological sort. A sorting file that sorts an unordered list of ordered pairs.
tower. A set of physical address and protocol information for a particular server. CDS uses this information to locate the system on which a server resides and to determine which protocols are available at the server. Tower values are contained in the CDS_Towers attribute associated with the object entry that represents the server in the cell namespace.
TPN. See transaction program name.
trace. (1.) To record data that provides a history of events occurring in the system. (2.) A record of the running of a computer program. It exhibits the sequences in which the instructions were run. (3.) To monitor system performance or aid in debugging programs.
trace daemon. Reads from the trace device driver and writes to the trace log file.
trace entry. Data recorded from a trace event.
trace ID. A unique identifier for a traced event.
trace log. A file where trace events are recorded.
trace table. A storage area that contains a record of the performance of computer program instructions.
trace template. Used by the trace formatter to determine how the data contained in trace entries should be formatted.
traceback. For the Ada debugger, a listing of the routines that are in the call chain above the code you are debugging. For example, if you set a breakpoint within an Ada procedure and request a call traceback, you see a list of all the procedures that called your Ada procedure, in the order in which they called it. All the calling procedures in the call chain are listed up to, but not including, the operating system calling the original highest level routine.
track. (1.) A circular path on the surface of a fixed disk or diskette on which information is magnetically recorded and from which recorded information is read. (2.) The path on a data medium associated with a single reading or writing component as the data medium moves past the component.
trailer. The portion of a message that contains control information. Trailers are used by the VAX Trailer Encapsulation Protocol. Trailer encapsulation allows the receiving host to receive data on a page-aligned boundary, which is a requirement for utilizing a page-mapped virtual memory environment.
trailer page. A trailer page that follows a printed file or a print job.
TRAN. Distributed Transaction Service.
transaction. (1.) An exchange between a workstation and a program, two workstations, or two programs that accomplish a particular action or result. Some examples are the entry of a customer's deposit and the updating of the customer's balance. (2.) In a batch or remote batch entry, a job or job step.
transaction family. Nested transactions that have a common ancestor belong to the same transaction family. All members of a transaction family commit together and drop their locks simultaneously.
transaction ID. See transaction identifier.
transaction identifier. A unique identifier assigned to each transaction, used to identify all actions associated with that transaction.
transaction program. A program that processes transactions in an SNA network. The two kinds of transaction programs are application transaction programs and service transaction programs. See also conversation .
transaction program name (TPN). The name of an application program that uses data communications to send or receive data to or from another application program.
transactional RPC. transactional remote procedure call.
transcript. In remote communications, a file that contains the written record of commands you enter on the remote system and the remote system's response to those commands.
transfer. To send data to one place and to receive data at another place.
transformation. In GL, a four-by-four matrix that helps determine the location where three-dimensional drawing will occur, the position of the viewpoint (the viewer's "eye"), and the amount of the scene encompassed and visible. Transformations occur at four points within the graphics pipeline: (1.) Modeling transformation, which maps modeling coordinates into world coordinates. All drawing primitives specify positions that are presumed to be positions in modeling coordinates. Modeling transformation can be used to move the thing being drawn. (2.) Viewing transformation, which maps from world coordinates to viewer coordinates. The origin of the viewer coordinate system can be thought of as the location of the viewer's "eye," and viewing transformations can be used to move the "eye" around in world coordinates. (3.) Projection transformation, which defines the boundaries of the clipping region. A projection transformation maps viewer coordinates to normalized device coordinates, and the clipping plane boundaries are at x = +/-w,y = +/-w, z= +/-w. Projection transformations can be used to define what region of the world is visible on the screen. (4.) Viewport, or NDC to DC transformation. The viewport transformation is not a full-fledged four-by-four transformation matrix; only three of the diagonal elements in the matrix can be changed. The viewport determines the mapping from normalized device coordinates to screen (device) coordinates. By default viewports are the same size as the window, although this can be adjusted.
transient. A program or subroutine that does not reside in main storage.
transit delay. In X.25 communications, the time it takes a packet to travel from one DTE to the other.
translation. (1.) The movement of something by a certain distance. (2.) In computer graphics, the moving of a display image in a straight line from one location to another. See also transformation.
translation lookaside buffer (TLB) . A table in the CPU that contains cross-references between the virtual and real addresses of recently referenced pages of memory.
translation table. (1.) A table that specifies the mapping of events or event sequences to procedure names. (2.) A string containing a list translating the events to procedure calls.
translation table list. See translation table.
translations. Action procedures that are called for an event or sequence of events.
transmission control characters. Special characters included in a message to control communication over a data link. For example, the sending station and the receiving station use transmission control characters to exchange information. The receiving station uses transmission control characters to indicate errors in data it receives.
Transmission Control Protocol (TCP). A communications protocol used in ARPA Internet and any network following the U.S. Department of Defense standards for inter-network protocol. Provides a reliable host-to-host protocol between hosts in packet-switched communications networks and in interconnected systems of such networks. It assumes that the Internet Protocol is the underlying protocol.
Transmission Control Protocol/Internet Protocol (TCP/IP). An industry-standard, nonproprietary communication protocol suite that allows connectivity between equipment from different manufacturers. Its development was funded by the Department of Defense Advanced Research Projects Agency. A communications subsystem that allows you to set up local area and wide area networks.
transmission services (TS). In SNA, a specification in a session activation request for transmission control (TC) protocols to be supported by a particular session (such as session-level pacing the usage of session-level requests). Each transmission services request defined is identified by a number.
transmit burst. A group of transmit packets that are sent without an intervening receive or time-out operation.
transparent. (1.) In communications, pertaining to transmissions that cannot interfere with data link control, regardless of format or content. Transparent transmissions are unrecognized by data link controls. (2.) In data transmission, pertaining to information that the receiving program or device does not recognize as transmission control characters. (3.) Pertaining to operations or data that are of no significance to the user.
transparent binding. A form of binding that allows the client application to bind to any available server exporting the desired interface
transparent mode. A method of binary synchronous text transmission in which only transmission control characters preceded by the data link escape(DLE) character are processed as transmission control characters.
Transport Layer. A network service that provides end-to-end communications between two parties, while hiding the details of the communications network. The TCP and ISO TP4 transport protocols provide full-duplex virtual circuits on which delivery is reliable, error free, sequenced, and duplicate free. UDP provides no guarantees (the connectionless RPC protocol provides some guarantees on top of UDP).
transport protocol. A communications protocol from the Transport Layer of the OSI network architecture, such as the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP).
trap. An unprogrammed, hardware-initiated, conditional jump to a specific address. It occurs as a result of an error or certain other conditions. A record is made of the location from which the jump occurred.
trap handler. A user-defined trap routine used when a trap occurs. See also exception.
Trash Can. In CDE, a container for deleted files or folders.
traversal. See keyboard traversal.
tree delta. A SCCS file that has a trunk, with changes identified by a release and level, and with one or more branches with deltas identified by an SID.
tree structure. A hierarchical calling sequence that consists of both a root segment and one or more levels of the segments called by way of the root segment.
tree view. In CDE, a view of a folder or files that includes all lower-level folders in the search path.
triangular array. A two-dimensional array in which active elements are found only on one side of a hypothetical axis delineated by the first and last elements of the array.
trimming loops. In GL, a set of oriented closed curves used to set the boundaries of a NURBS surface. See also NURBS.
Trivial File Transfer Protocol. Transfers files between hosts using minimal protocol.
troff. A phototypesetting utility originally designed to support a Graphics Systems phototypesetting machine, but now capable of supporting a variety of phototypesetters.
true color. In Enhanced X-Windows, (1.) A degenerate case of direct color in which the subfields in the pixel value directly encode the corresponding RGB values. That is, the color map has predefined read-only RGB values. The values are typically near-linear increasing ramps. (2.) Also TrueColor, a value. (3.) Refers to the use of 24-bits per pixel direct RGB, where there are 8 bits (256 levels) of red, 8 bits (256 levels) of green, and 8 bits (256 levels) of blue, for a total of 256*256*256 or 16,777,216 different combinations of red, green, and blue intensities. The number of different colored pixels that can then be simultaneously displayed is only limited by the number of pixels displayable from the frame buffer.
truncate. (1.) To end a computational process in accordance with some rule; for example, to end the evaluation of a power series at a specified term. (2.) To remove the beginning or ending elements of a string. (3.) To drop data that cannot be printed or displayed in the line width specified or available. Contrast with fold. (4.) To shorten a field or statement to a specified length.
trust peer. A characterization of one cell with respect to another with which the cell maintains a mutual authentication surrogate.
trusted computing base (TCB). The part of the system that contains all the elements that support the security policy of the system. The trusted computing base includes all hardware, microcode, and software that protect information on the system.
trusted device. An IPL device such as a fixed disk or diskette drive, where the IPL ROM code can find an IPL record and IPL code.
trusted environment. A clean environment in which all untrusted processes have been killed order to ensure security for communications between the user and the operating system.
trusted path. See trusted environment.
trusted process. A process in which a particular standard of security has been met.
try block. A C++ block in which a known exception is passed to a handler.
TS. See transmission services.
tty. In the operating system, any device that uses the termio standard terminal device interface. tty devices typically perform input and output on a character-by-character basis.
tty device. See tty.
tuning. See hand tuning.
turnaround. Changing a communications line from transmit mode to receive mode, or from receive mode to transmit mode.
twist. A rotation around the line of sight.
two and one-half dimension. See 2-1/2 dimension.
two-way channel. In X.25 communications, a logical channel that allows both incoming and outgoing calls. Contrast with one-way channel.
twos complement. The radix complement in the pure binary numeration system. The twos complement is derived by taking the ones complement and then adding one to the resulting number. In a twos complement system, the twos complement of a number n is -n. See also ones complement.
type. (1.) In Enhanced X-Windows, an arbitrary atom used to identify the data. A type is solely for the benefit of clients and is not interpreted by the server. Enhanced X-Windows predefines type atoms for many frequently used types. Clients also can define new types. (2.) In Pascal, see data type. (3.) In NCS, a class of object. All objects of a specific type can be accessed though the same interface or interfaces. (4.) In Ada language, a type characterizes both a set of values, and a set of operations applicable to those values. A type definition is a language construct that defines a type. A particular type is either an access type, an array type, a private type, a record type, a scalar type, or a task type. (5.) In XOM, a category into which attribute values are placed on the basis of their purpose.
type compatibility. See compatible types.
type conversion. A routine or set of routines that enables an application to change a specified string of data from one declared type to another. In AIXwindows programming, type conversion is performed on strings using conversion information contained in the MRM database.
type declaration. The specification of the type and, optionally, the length of a variable or function in a specification statement.
type definition. A definition of a name for a data type.
type identifier. The name given to a declared type. See also type specifier.
type regrouping. An optimization that involves reodering mixed-type expressions so that all variables of a given type are grouped together.
type specifier. A name of a data type.
type style. The form of characters of a given size, style, and design within the set of the same font.
type UUID. (1.) A UUID that permanently identifies a particular type. Both the RPC run time library and the Location Broker use type UUIDs to specify types. (2.) In DCE RPC, the UUID that identifies a particular type of object and an associated manager. See also object, Universal Unique Identifier UUID.
typematic key. A key that, when held down, repeats its function multiple times.