0-9 A B C D E F G H I J K L M N O P Q R S T U V W XYZ

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abbreviated address calling:
Calling that enables a user to employ an address having fewer characters than the full address when initiating a call.

An ordered and shortened representation of data that retains the identity of the data element that is represented.

abnormal end.

ablative optical disk:
A WORM optical disk providing for data to be written onto the disk as marks in the form of holes or pits in a recording layer.

abnormal end (abend):
Synonym for abnormal termination.

abnormal termination:
An unplanned cessation of processing. Synonymous with abnormal end, abend.

To terminate abruptly a processing activity in a data processing system because it is impossible or undesirable for the activity to proceed.

aborted connection:
A disconnection that does not follow established procedures. An aborted connection may enable other entities to gain unauthorized access.

abort sequence:
A specified bit pattern, occurring anywhere in the bit stream, that is used to terminate transmission of a frame prematurely.

abort statement:
A simple statement that causes one or more tasks to become abnormal, preventing any further rendezvous with such a task.

absolute address:
A direct address that identifies a location without reference to a base address. An absolute address may itself be a base address.

absolute assembler:
An assembler that produces absolute code.

absolute code:
Code in which all addresses are absolute addresses.

absolute coding:
Coding that uses computer instructions with absolute addresses. Synonymous with specific coding.

absolute command:
A display command using absolute coordinates.

absolute coordinate:
Any one of the coordinates identifying the position of an addressable point with respect to the origin of a specified coordinate system.

absolute error:
(1) The algebraic result of subtracting a true, specified, or theoretically correct value from the value computed, observed, measured, or achieved. (2) The amount of error expressed in the same units as the quantity that contains the error. (3) Loosely, the absolute value of the error. For example, the magnitude of the error without regard to its algebraic sign.

absolute instruction:
Deprecated synonym for absolute command.

absolute loader:
A program that copies load modules, within which all addresses are absolute addresses, from external storage to internal storage, thus address adjustment is unnecessary. Contrast with relocating loader.

absolute value:
A value for position and orientation within the space of a virtual world as measured from a single, constant point of origin.

absolute vector:
In computer graphics, a vector whose start and end points are specified in absolute coordinates.

abstract class:
A class of which no objects are created; rather the class is used to define subclasses and objects from the subclasses. Contrast with generic module.

abstract data type (ADT):
The characteristics of a data type independent of implementation details; an abstract data type cannot be directly instantiated.

A view of an object that focuses on the information relevant to a particular purpose and ignores the remainder of the information.

abstract symbol:
(1) A symbol whose meaning and use have not been determined by general agreement, but have to be defined for each application of the symbol. (2) A symbol whose form does not suggest its meaning, but must be defined for each specific set of applications.

abstract syntax:
In the context of the OSI Presentation Service, the specification of application layer data or application protocol control information by using notation rules that are independent of the encoding technique used to represent them.

A/B switch box:
An enclosure that contains a two-position selector switch to allow the user to choose between two inputs or outputs.

acceleration card:
Synonym for accelerator card.

accelerator board:
Synonym for accelerator card.

accelerator card:
A circuit board designed to speed up some functions of a computer. Synonymous with accelerator board, acceleration card.

acceptance test:
A test of a system or functional unit, usually performed by users on their premises after installation, with the participation of the vendor to ensure that contractual requirements are met.

accept statement:
A compound statement within a server task, that causes this server task to wait for another task or for the main program to execute an entry call statement for task synchronization.

(1) The means, ability, or permission to approach, enter, or use a resource. (2) The use of an access method. (3) In computer security, a specific type of interaction between a subject and an object that results in the flow of information from one to the other.

access arm:
In a disk drive, an arm on which magnetic heads are mounted.

access category:
In computer security, a category to which entities may be assigned, based on the resources that the entity is authorized to use.

access control:
A means of ensuring that resources can be accessed only by authorized entities in authorized manners.

access control field:
In a packet communication system, a bit pattern that
  1. distinguishes a frame from a token,
  2. indicates the data stations that may use the token,
  3. indicates when the frame should be canceled, and
  4. allows stations to request the next token.

access control key:
Synonym for privacy key.

access controller:
In an information resource dictionary system with entity-level security, a pair of locks, one for read access, the other for write access. Locks may be used for other purposes, such as to permit execution.

access control list:
A list of entities, together with their access rights, that are authorized to access a resource. Synonymous with access list.

access control lock:
Synonym for privacy lock.

access key:
In an information resource dictionary system with entity-level security, an authorization to perform a set of operations on an entity secured by a lock.

access level:
The level of authority required from an entity to access a protected resource; for example, the authority to access information at a particular security level.

access list:
Synonym for access control list.

access lock:
Synonym for privacy lock.

access management service:
A service that enables a user agent and a message transfer agent to establish access to one another and to manage associated information.

access matrix:
A two-dimensional array, one dimension of which represents objects and the other dimension represents subjects, where the intersections represent permitted access types.

access mechanism:
A mechanism that is responsible for moving an access arm or a comb. Synonymous with actuator.

access method:
A technique to obtain the use of data, the use of storage in order to read or write data, or the use of an input/output channel to transfer data. For example, direct access method, indexed access method, sequential access method.

access mode:
A technique that is used to obtain a particular logical record from, or to place a particular logical record into, a file assigned to a mass storage device; for example: sequential mode, direct mode.

access name:
In an information resource dictionary, the name by which an entity is known to the user interfaces. It is the combination of an assigned access name and a version identifier that together serve as the primary identifier of each entity.

access path:
A chain of addresses that leads to the desired data. There may simultaneously exist more than one access path for a given data item.

access-path independence:
The separation of a logical data description from its access path so that changes to the access path do not require changes to the logical data description in a program.

access period:
A period of time during which specified access rights prevail.

access permission:
All of a subject's access rights with respect to some object.

access point:
In a computer network, a point at which the user may connect to the network.

access provider:
An organization that provides users with access to a computer network, for example, an Internet Service Provider (ISP). The access provider and the content provider may be the same organization.

access right:
Permission for a subject to access a particular object for a specific type of operation; for example, permission for a process to read a file but not write to it.

access time:
The time interval between the instant at which a call for data is initiated and the instant at which the delivery of data is completed; access time equals latency plus transfer time. (Figure 1 - Access time).

access type:
(1) In computer security, a type of operation specified by an access right; for example, read, write, execute, append, modify, delete, create. (2) Synonym for pointer type.

access unit (AU):
In electronic mail, a functional unit that links a message transfer system to another communication system by which its users indirectly access the message handling system.

The property that ensures that the actions of an entity may be traced uniquely to that entity.

accountability information:
In computer security, an audit trail for security purposes.

accounting machine:
(1) A keyboard-actuated machine that prepares accounting records.(2) A machine that reads data from external storage media, such as cards or tapes, and automatically produces accounting records or tabulations, usually on continuous forms.

In computer security, the authorization and approval, granted by a designated authority to a data processing system, computer network, organization, or individual, to process sensitive information or data.

A register in which one operand of an arithmetic operation or logic operation can be stored and subsequently replaced by the result of that operation.

(1) A qualitative assessment of freedom from error. (2) A quantitative measure of the magnitude of error, preferably expressed as a function of one minus the relative error, a high value of this measure corresponding to a small error.

accuracy control character:
A control character used to indicate whether the data with which it is associated are in error, are to be disregarded, or cannot be represented on a particular device. Synonymous with error control character.

The acknowledge character.

acknowledge character (ACK):
A transmission control character transmitted by a receiver as an affirmative response to a sender; an acknowledge character may also be used as an accuracy control character.

An affirmative response, by a receiver, to a sender, indicating that transmitted data have been received.

acoustic coupler:
A device that interconnects a communicating unit with a telephone handset by converting sound signals to or from electrical signals.

acoustic delay line:
A delay line whose operation is based on time of propagation of sound waves in a given medium. Synonymous with sonic delay line.

acoustic emanations:
In computer security, sound inadvertently transmitted from information processing equipment that might permit unauthorized access to information.

acoustic signal:
A signal consisting of sound which conveys data.

acoustic storage:
A storage device consisting of acoustic delay lines.

association control service element.

In artificial intelligence, an operation performed by an actor in a thematic role.

action bar:
Synonym for menu bar.

action description:
In a conceptual schema language, a linguistic object describing an action or permissible action.

(1) In artificial intelligence, an operation that allows the firing of a rule or the invocation of a program or of a subprogram. (2) In programming, the establishment of an activation record.

activation function:
In artificial neural networks, a function that computes the output value of an artificial neuron based on its input values and its current connection weights. The output value may be continuous or discrete.

activation record:
In a data processing system, the data object that represents an instance of a task or of a subprogram and that contains data values and process status data for that instance. An activation record may contain parameters, results, local data, etc.

active matrix display:
Synonym for active matrix display device.

active matrix display device:
A display device that gives every pixel on the screen its own control. Example: TFT active matrix, where TFT is the abbreviation of "thin-film transistor". This allows for better contrast and less motion smearing. Synonymous with active matrix display.

active threat:
Any threat of a deliberate unauthorized change to the state of a data processing system; for example, a threat that would result in modification of messages, insertion of spurious messages, masquerade, or denial of service. (Figure 57 - Levels of security risks).

active vocabulary:
Synonym for spoken vocabulary.

active window:
Any of a set of windows currently manipulated.

active wiretapping:
Wiretapping with the purpose to modify or insert data.

activity content:
Synonym for activity inventory.

activity inventory:
In an information processing system, a list of all of the functions and processes and their interdependencies. Synonymous with activity content.

(1) In artificial intelligence, a known entity that fills a thematic role in a script. (2) In hypermedia and multimedia, an animated interactive multimedia object.

actual argument:
Synonym for actual parameter.

actual parameter:
A parameter, such as an expression, identifier, or other language construct, used in a call or in a generic instantiation for associating a data object with a corresponding declaration. The corresponding declaration is called formal parameter. Synonymous with actual argument.

actual recipient:
A potential recipient for which delivery or affirmation takes place. The status of potential recipient changes into actual recipient on the event of delivery or affirmation.

actual transfer rate:
The average number of bits, characters, or blocks transferred per unit of time between two points. Synonymous with transfer rate.

Synonym for access mechanism.

A measure of the sharpness of a transition between two regions of an image.

A specific general-purpose, high-level language, originally developed under the aegis of the U.S. Department of Defense to provide a means, independent of proprietary machine languages, for implementing embedded systems and especially suitable for very large applications with long lifetimes; it features structured programming, data structures with strong typing, multitasking, facilities for object-oriented programming, private data types, packages, exception handlers, and generic program units. The design evolved from ALGOL and Pascal.

adaptive learning:
A learning strategy that adjusts internal knowledge according to advice from an external knowledge source, or transforms newly acquired information according to existing knowledge.

adaptive neural network:
A neural network that is able to adjust its performance characteristics according to changes in its environment.

adaptive refinement:
In virtual reality, taking advantage of a reduced level of a participant's interactivity with the artificial-reality engine to increase the level of detail of the immediate surroundings.

adaptive resonance theory network:
In machine learning, a network in which the learning algorithm either updates the stored prototypes characterizing categories if the input pattern is sufficiently similar to one of them, or creates a new category with the input as prototype. ART networks implement a compromise between plasticity (the ability to learn) and stability (no erasure or corruption of existing knowledge). Synonymous with ART network.

adaptive training:
In speech processing, training capable of modifying and updating a speech template to improve performance.

A/D converter:
Synonym for analog-to-digital converter.

Analog-to-digital converter.

A functional unit whose output data is a representation of the sum of the numbers represented by its input data.

A functional unit that acts as an adder or subtracter, depending upon the control signal received; an adder-subtracter may be constructed so as to yield the sum and the difference at the same time.

Synonym for expansion board.

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