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touch pad:
A touch-sensitive pointing device that allows pointing and clicking.

touch screen:
A display device that allows the user to interact with a data processing system by touching an area on its screen. Synonymous with touch sensitive screen.

Pertaining to a device that allows a user to interact with a computer system by touching an area on the surface of the device with a finger, pencil, or other object.

touch sensitive screen:
Synonym for touch screen.

tournament sort:
A repeated selection sort in which each subset consists of no more than two items.

(1) A record of the execution of all or part of a program, showing the sequence of instructions or statements executed, the operands involved, and the results. (2) To produce a trace.

trace program:
A program that produces a trace.

Synonym for boundary tracing.

tracing facility:
In a knowledge-oriented programming language or programming tool, a means of displaying the rules executed along with the values of the variables used.

tracing routine:
A routine that provides a historical record of specified events in the execution of a program.

(1) On a data medium, a path associated with the sequential access of signal or data. A given data medium may be formatted with multiple parallel tracks, such as in concentric circles on a magnetic disk or a single track such as a continuous spiral as typically used on optical disks. In some media, such as magnetic tape, multiple tracks are read in parallel to assemble elementary data units (e.g., bits) into larger units of data, such as bytes. (2) In a multimedia animation, a representation medium referencing movie data that can be stored on a storage device. Track may refer to a representation medium that contains references to the animation data, that may be stored as images or sounds on hard disks, floppy disks, compact disks, or other devices.

track-and-hold unit:
A functional unit whose output analog variable is equal to either the input analog variable or a sample of this variable selected by the action of an external Boolean signal. When tracking, the functional unit follows the input analog variable; when holding, it holds the value of the input analog variable at the instant of switching.

track-and-store unit:
Synonym for track-and-hold unit.

A locator or a pointing device that employs a ball that is rotatable about its center. Synonymous with control ball. Contrast with mouse.

track density:
The number of tracks per unit length, measured in a direction perpendicular to the tracks. The track density is inversely related to the track pitch.

In computer graphics, the action of moving a tracking symbol.

tracking symbol:
A symbol on the screen that indicates the position corresponding to the coordinate data produced by a locator.

track pitch:
The distance between centerlines of adjacent tracks, measured in a direction perpendicular to the tracks. The track pitch is inversely related to the track density.

traffic analysis:
The inference of information from observation of traffic flow; for example, analysis of the presence, absence, amount, direction, and frequency of traffic.

traffic padding:
A countermeasure that generates spurious data in transmission media to make traffic analysis or decryption more difficult.

trailer label:
Synonym for end-of-file label.

trailing decision:
A loop control that is executed after the loop body.

trailing zero:
In positional notation, a zero in a less significant digit place than the digit place of the least significant nonzero digit of a numeral.

In artificial neural networks, a procedure for teaching a neural network to make an association between a sample of input values and the correct output values.

(1) A command, message, or input record that explicitly or implicitly calls for a processing action, such as updating a file. (2) An exchange between an end user and an interactive system. (3) In a database management system, a unit of processing activity that accomplishes a specific purpose. (4) A unit of processing that is activated by a command, message, or input and that accomplishes a specific purpose for the user.

transaction call:
In programming, a function call that permits a task to request a rendezvous with another task.

transaction file:
A file containing relatively transient data that, for a given application, is processed together with the appropriate master file.

transaction processing:
The operating mode in which data or jobs are processed immediately after they are received.

transaction processing service:
An application service in a distributed system that enables two or more processes, through interactive communication, to complete transactions.

To copy data from one data medium to another, converting them as necessary for acceptance by the receiving data medium.

(1) The sending of data from one location and the reception thereof at another. Contrast with transmission, move, transmit. (2) In electronic mail, a transmittal step in which one message transfer agent conveys a message, probe, or report to another message transfer agent.

transfer check:
A check on the accuracy of a data transfer.

transfer interpreter:
A device that prints on a punched card the characters corresponding to hole patterns punched in another card.

transfer rate:
Synonym for actual transfer rate.

transferred information:
Synonym for transinformation content.

transfer syntax:
In the context of the OSI Reference Model, that concrete syntax used in the transfer of data between open systems.

transfer time:
The time interval between the instant at which a transfer of data starts and the instant at which the transfer is completed. (Figure 1 - Access time).

To change the form of data according to specified rules, without fundamentally changing the meaning of the data.

transient error:
Synonym for soft error.

transinformation content:
The difference between the information content I(x) conveyed by the occurrence of an event x, and the conditional information content I(x|y) conveyed by the occurrence of the same event, given the occurrence of another event y; in mathematical notation the measure is:
T(x,y) = I(x) - I(x|y).
The two events x and y are particularly a message at the message source of a channel and a message at the message sink of the channel. The transinformation content can also be expressed as:
T(x,y) = I(x) + I(y) - I(x,y)
where I(y) is the information content of the event y. From this follows that it is symmetric in x and y:
T(x,y) = T(y,x)
Synonymous with transferred information, transmitted information, mutual information.

In data communications, a transient phenomenon separating two successive signal elements having different significant conditions in a digital signal. (Figure 21 - Components of an idealized discrete signal)

translate phase:
In programming, the logical subdivision of a run that includes the execution of the translator.

In computer graphics, the process or the result of applying the same displacement to the positions of one or more display elements.

In programming, the process or the result of transforming, without any modification of the original meaning, all or part of a program expressed in one programming language into another programming language.

translational sweep:
Synonym for extrusion.

translation duration:
The amount of time needed to translate a program.

translation program:
Synonym for translator.

translation time:
Any instant at which translation takes place.

One or more programs that can translate. Synonymous with translation program.

translator directive:
A language construct for controlling the translation of a program.

To represent characters or words in the closest corresponding characters of another character set.

The sending, for reception elsewhere, of a signal, a message, or other form of data. Contrast with transfer.

transmission block:
A group of bits or characters transmitted as a unit, usually with an encoding procedure for error control purposes.

transmission channel:
A means of transmission of signals in one direction between two points. A transmission channel may be provided, for example, by frequency division multiplexing or time division multiplexing. Synonymous with channel.

transmission control character:
A control character used to control or facilitate data transmission between data terminal equipment.

Transmission Control Protocol:

Transmission Control Protocol/Internet Protocol:

transmission frame:
Synonym for frame.

transmission line:
Synonym for line.

transmission medium:
A natural or artificial medium that conveys signals.

transmission path delay:
The time required for a bit to travel between two data stations in a network.

To send from one location for reception elsewhere. Contrast with move, transfer.

In electronic mail, the conveyance or attempted conveyance of an information object from a source to its potential recipients. A transmittal consists of a sequence of transmittal steps and transmittal events.

transmittal event:
In electronic mail, an event that occurs within the message transfer system during the transmittal of a message.

transmittal step:
In electronic mail, the process of conveying an information object within the message handling environment from one functional unit to another.

transmitted information:
Synonym for transinformation content.

transport layer:
In OSI, the layer that provides a reliable end- to-end data transfer service. The transport layer adds end-to-end integrity to the service provided by the network layer. (Figure 47 - The Open Systems Interconnection Reference Model).

In security, encryption that rearranges bits or characters according to some scheme. The resulting ciphertext is called transposition cipher.

A suspension of the normal sequence of execution caused by a special condition in the process, such as an attempt to divide by zero. Logic may be available to correct the problem to permit the process to proceed or the program may be terminated.

A hidden software or hardware mechanism, usually created for testing and troubleshooting, that may be used to circumvent computer security.

A data structure containing nodes that are linked together hierarchically with at most one parent node for each node, and with only one root node.

tree network:
A network in which there is exactly one path between any two nodes. (Figure 43 - Network topologies).

tree search:
In a tree structure, a search in which it is possible to decide, at each step, which part of the tree may be rejected without further search.

tree structure:
A data structure that arranges entities or attributes as nodes, with at most one parent node for each node, and with only one root node. Each node is considered an ancestor of all lower-level nodes to which it is connected. The root node is the ancestor of all other nodes.

tributary station:
On a multipoint connection or a point-to-point connection, using basic mode link control, any data station other than the control station.

trigger circuit:
A circuit that has a number of states, at least one being a stable state, and is designed so that a desired transition from a stable state to another state can be initiated by the application of a suitable pulse.

triple-pass scanner:
A color scanner that performs one scanning pass on an image for each of the primary colors of light.

triple precision:
Characterized by the use of three computer words to represent a number to accommodate the required precision.

A byte composed of three binary elements. Synonymous with 3-bit byte.

Trojan horse:
In computer security, an apparently harmless program containing malicious logic that allows the unauthorized collection, falsification, or destruction of data.

truncated binary exponential backoff:
In a CSMA/CD network, the algorithm used to schedule retransmission after a collision such that the retransmission is delayed by an amount of time derived from the slot time and the number of attempts to retransmit.

(1) In strings, the deletion or omission of a leading or of a trailing portion of a string in accordance with specified criteria. (2) The termination of a computation process, before its final conclusion or natural termination, if any, in accordance with specified rules.

truncation error:
An error caused by the deletion or omission of a portion of a positional representation.

trunk cable:
A cable connecting trunk coupling units for the purpose of allowing communication among data stations. (Figure 3 - Interconnection of data stations on a trunk cable).

trunk connecting unit:
Synonym for trunk coupling unit.

trunk coupling unit (TCU):
A physical device that connects a data station to a trunk cable by means of a drop cable. Synonymous with trunk connecting unit. (Figure 3 - Interconnection of data stations on a trunk cable).

trusted computer system:
A data processing system that provides sufficient computer security to allow for concurrent access to data by users with different access rights and to data with different security classification and security categories.

truth maintenance system:
A knowledge-based system that maintains the truth of its knowledge base by keeping track of the dependencies between beliefs.

truth table:
(1) A table that describes a logic function by listing all possible combinations of input values and by indicating, for each combination, the output value. (2) An operation table for a logic operation.

time slot.

terminate and stay resident.

Dynamic display of the rotation of display elements about an axis the orientation of which is continuously changing in space.

A technique for connecting two networks via a third network while totally isolating the connected traffic from other traffic in the third network. (Figure 64 - Tunneling).

In a relational database, a part of a relation that uniquely describes an entity and its attributes. A tuple can be represented by one row of a relation table.

Turing machine:
A mathematical model of a device that changes its internal state and reads from, writes on, and moves a potentially infinite tape, all in accordance with its present state, thereby constituting a model for computer-like behavior.

turnaround time:
The elapsed time between submission of a job and the return of the complete output.

turnkey system:
A data processing system that is ready to use when installed, and supplied to the user in a ready-to-run condition possibly customized to a specific user or application. Some preparatory work on the user's data may be required.

turn-on stabilizing time:
The time interval between the instant power is applied to a device and the instant at which the device performs according to its operating specifications.

twisted pair:
A transmission medium that consists of two insulated electrical conductors twisted together.

two-address instruction:
An instruction that contains two address parts; for example, an instruction to add the contents of storage location A to the contents of storage location B.

two and one-half dimensional (2.5D):
Pertaining to a two-dimensional graphic representation in which a three-dimensional effect is produced by assigning an occlusion priority to overlapping objects.

two-out-of-five code:
A binary-coded decimal notation in which each decimal digit is represented by a binary numeral consisting of five bits out of which two are of one kind, conventionally ones, and three are of the other kind, conventionally zeros. The usual weights are 6-3-2-1-0 except for the representation of zero which is then 00110.

twos complement:
The radix complement in the binary system.

two-way alternate communication:
Data communication such that data may be transferred in both directions, but only one direction at a time.

two-way simultaneous communication:
Data communication such that data are transferred in both directions at the same time.

type conversion:
Transformation of the representation of a data value of one data type to that of another data type, usually performed to avoid an illegal data type mismatch. Type conversion among numeric types frequently is permitted but may cause loss of accuracy, precision, or both.

typed body service:
A service that permits conveying the nature and characteristics of each of the parts within the body of an interpersonal message. The characteristics include encoded information type.

In programming languages, assigning a specific data type to each object; for example, integer, real, logical.

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