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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atomic type:
A data type, each data object of which consists of a single nondecomposable data value.

attachment unit interface (AUI):
In a data station on a local area network, the interface between the medium attachment unit and the data terminal equipment. (Figure 3 - Interconnection of data stations on a trunk cable).

attack:
An attempt to violate computer security; for example, malicious logic, wiretapping. (Figure 57 - Levels of security risks).

attribute:
(1) A named property or characteristic of one or more entities; for example, color, weight, sex. (2) A property inherent in an entity or associated with that entity for database purposes. (3) In electronic mail, a data item that describes a user or a distribution list and that can be used to locate this user or list in relation to the physical or organizational structure of a message handling system; for example: names, addresses. (Figure 65 - Selected O/R address attributes).

attribute domain:
The set of all possible values of a given attribute.

attribute relationship:
A perceived association among attributes.

attribute type:
The data type for a given attribute. The name of a column of a relation table can be viewed as the name of an attribute type.

attribute value:
A specific occurrence of an attribute; for example, "blue" is an attribute value for the attribute "color".

AU:
access unit.

audio card:
Synonym for sound card.

audit:
In security, to conduct an independent review and examination of system records and activities in order to test the adequacy and effectiveness of data security and data integrity procedures, to ensure compliance with established policy and operational procedures, and to recommend any necessary changes.

audit trail:
(1) Data describing a sequence of associated events that may be used to trace the transactions that have affected the contents of a record. (2) A chronological record of system activities that is sufficient to enable the reconstruction, review, and examination of the sequence of environments and activities surrounding or leading to each event in the path of a transaction from its inception to output of final results. (3) In computer security, data collected for the potential use in a security audit.

augmented reality:
In virtual reality, an enhanced perception in which a person relies on the real world as a frame of reference but uses a transparent (rather than opaque) display or a nonintrusive means to augment the perception of reality.

AUI:
attachment unit interface.

authentication:
In security, the act of verifying the claimed identity of an entity.

authentication exchange:
In computer security, a mechanism intended to ensure the identity of an entity by means of an information exchange.

authentication information:
In computer security, information used to establish the validity of a claimed identity of an entity.

author-defined link:
A hyperlink defined during the development of a hypermedia application.

author-defined path:
A hypermedia path defined during the development of a hypermedia application.

authoring language:
(1) A problem-oriented language designed to develop courseware for computer-aided instruction. (2) In hypermedia and multimedia, a high-level language that enables a user to create new multimedia or hypermedia applications, for example: Delphi, Java, Lingo.

authorization:
(1) The rights granted to a user to access, read, modify, insert, or delete certain data, or to execute certain programs. (2) The granting of rights, which includes the granting of access based on access rights.

auto-attendant:
Synonym for automated attendant.

auto-forward:
In electronic mail, the automatic action of forwarding received messages to a predefined new intended recipient.

automate:
To make a process or equipment automatic.

automated attendant:
A voice response system for helping routing of calls and/or messages via either touch-tone or spoken requests. An automated attendant is a type of voice server. Synonymous with auto-attendant.

automatic:
Pertaining to a process or equipment that, under specified conditions, functions without human intervention.

automatic answering:
Answering in which the called data terminal equipment (DTE) automatically responds to the calling signal. The call may be established whether or not the called DTE is attended.

automatic calling:
In a data network, calling in which the elements of the selection signal are entered into the data network contiguously at the full bit rate. The selection signal is generated by the data terminal equipment. A limit may be imposed by the design criteria of the network to prevent more than a permitted number of unsuccessful call attempts to the same address within a specified period of time.

automatic carriage:
A control mechanism for a typewriter or other listing device that can automatically control the feeding, spacing, skipping, and ejecting of paper or preprinted forms.

automatic check:
A check performed by equipment built-in specifically for checking purposes. Synonymous with built-in check.

automatic data processing (ADP):
Data processing performed by a computer system. Loosely, a synonym for data processing.

automatic footnote tie-in:
A function that automatically places a footnote at the bottom of the page on which the footnote reference appears or at a specified location.

automatic function:
A machine function or series of machine functions controlled by the program and carried out without the assistance of an operator.

automatic page numbering:
The capability of a text processor to automatically generate page numbers on successive pages of a document. This term should not be confused with automatic pagination.

automatic pagination:
The automatic arrangement of text into pages according to preset page layout parameters. This function enables the user to enter text without regard for final page endings. This term should not be confused with automatic page numbering.

automatic paragraph numbering:
The capability of a text processor to automatically generate sequential paragraph identifiers on successive paragraphs of a document in a predefined manner.

automatic programming:
The process of using a computer to perform some stages of the work involved in preparing a program.

automatic speech recognition (ASR):
Synonym for speech recognition.

automation:
(1) The conversion of processes or equipment to automatic operation, or the result of the conversion. (2) The theory, art, or technique of making a process automatic. (3) The investigation, design, development, and application of methods of rendering processes automatic, self-moving, or self-controlling.

auto-reply:
In electronic mail, the automatic creation of a message as an answer to a received message and the automatic assigning of the originator as the intended recipient.

auxiliary operation:
An offline operation performed by equipment not under control of the processing unit.

auxiliary storage:
Synonym for external storage.

availability:
(1) The ability of a functional unit to perform a required function under given conditions while the required external resources are provided and the functional unit is accessible to the user. The word "user" here means any person or functional unit that receives the service of, or operates, the functional unit in question, and is used in a collective sense. For example, if the functional unit is accessible to the operating staff, it is considered to be accessible to the user. "Availability" can be quantified as the ratio of a) the total time during which the functional unit is in a state to be able to perform a required function under given conditions to b) the length of the interval. (2) In computer security, the property of data or of resources being accessible and usable on demand by an authorized entity.

available:
Pertaining to a state and condition where a functional unit is capable of performing a required function while the required external resources are provided and the functional unit is under the user's control.

avatar:
An abstract representation of a participant in a virtual world. The physical dimensions of the avatar are used for collision detection and terrain following.

average conditional information content:
Synonym for conditional entropy.

average information content:
Synonym for entropy.

average information rate:
The quotient of the character mean entropy H'  by the mean duration of a character; in mathematical notation, this quantity is
H* = H'/t(X)
where X = {x1...xn} is the set of characters xi(i=1...n) and
n
t(X)   =
p(xi) t(xi)
i=1
is the mean value of the duration t(xi) of a character xi which occurs with probability p(xi). The average information rate may be expressed in a unit such as the shannon per second.

average transinformation content:
Synonym for mean transinformation content.

average transinformation rate:
The quotient of the character mean transinformation content T' by the mean duration of a pair of input and output characters; in mathematical notation, this quantity is
T* = T'/t(X,Y)
where X = {x1...xn} is the set of input characters xi(i=1...n), Y={y1...ym} is the set of output characters yj(j=1...m), and
n
m
t(X,Y)   =
p(xi,yj) t(xi,yj)
i=1
j=1
is the mean value of the duration t(xi,yj) of the pair of characters (xi,yj) which occurs with joint probability p(xi,yj). The average transinformation rate may be expressed in a unit such as the shannon per second.

axiom:
In a conceptual schema language, any closed sentence that is asserted to be considered as such by an authorized source.

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