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data processing (DP):
The systematic performance of operations upon data; for example, arithmetic or logic operations upon data, merging or sorting of data, assembling or compiling of programs, or operations on text, such as text editing, sorting, merging, storing, retrieving, displaying, or printing. The term data processing must not be used as a synonym for information processing. Abridged term for automatic data processing.

data processing center:
Synonym for computer center.

data processing system:
One or more computers, peripheral equipment, and software that perform data processing. Data processing systems may also include information processing capability. Synonymous with computer system, computing system.

data protection:
The implementation of administrative, technical, or physical measures to guard against the unauthorized access to data.

data reconstitution:
A method of data restoration by assembling data from components available in alternative sources.

data reconstruction:
A method of data restoration by analyzing original sources.

data reduction:
The transformation of raw data into a more useful form.

data restoration:
The act of regenerating data that have been lost or contaminated. Methods include copying data from archive, data reconstitution from alternative sources, or data reconstruction from source data.

data security:
Computer security applied to data.

data-sensitive fault:
A fault that may be detected as an error as a result of the processing of a particular pattern of data.

data signaling rate (DSR):
The bit rate in parallel transmission. The data signaling rate is given by
(1/Ti) log2ni
i = 1
where m is the number of parallel transmission channels; Ti is the significant interval for the i-th channel expressed in seconds; ni is the predefined number of significant conditions in the i-th channel

data sink:
The functional unit that accepts transmitted data.

data source:
The functional unit that provides data for transmission.

data station:
A functional unit that provides data for transmission, that accepts transmitted data, and that performs all functions necessary for communication with another functional unit. (Figure 3 - Interconnection of data stations on a trunk cable). (Figure 18 - Half of a data link).

data streaming:
The transfer of data over an interface so that the data can be processed in a steady and continuous stream. For example: audio streaming, video streaming.

data striping:
A RAID method that distributes data across two or more hard disks.

data structure:
A physical or logical relationship among units of data.

data structuring rule:
A rule that specifies the structure of data as instances of a certain data type.

data suit:
Synonym for body suit.

data switching exchange (DSE):
In data communications, the equipment installed at a single location to perform switching between data circuits.

data terminal equipment (DTE):
In data communications, that part of a data station that serves as a data source, a data sink, or both. The DTE may be connected directly to a computer, or may be part of it. (Figure 3 - Interconnection of data stations on a trunk cable). (Figure 18 - Half of a data link).

data trace:
Synonym for variable trace.

data transfer phase:
In data communications, that phase of a call during which user data may be transferred between data terminal equipments that are interconnected via a network.

data transmission:
The sending of data from one place to another by means of signals over a channel.

data type:
A defined set of acceptable values of a specified data structure and a set of permissible operations on these values as operands. For example, an integer type has a very simple structure that contains the representation of a value chosen from a specified range of whole numbers, and the permissible operations include the usual arithmetic operations on these integers. The term "type" may be used instead of "data type" when there is no ambiguity. Synonymous with datatype. (Figure 19 - Examples of data types).

Synonym for data type.

data validation:
The checking of data for correctness or compliance with applicable standards, rules, and conventions. Data validation may include format checks, completeness checks, check key tests, reasonableness checks, and limit checks.

data value:
For a given data object, an instance of a value of the associated data type. In principle, data value should be distinguished from "function value" in mathematics, from "value of a number" and "position value" in numeric representation.

data volatility:
A characteristic of data pertaining to the rate of change of these data over time.

data warehouse:
A database, frequently very large, that represents the transactional data of an entire enterprise.

data zone:
Synonym for user data area.

A circuit board attached to another board such as the motherboard.

database administrator.

database management system.

DC1, DC2, DC3, DC4:
The device control characters.

data-circuit terminating equipment.

digital differential analyzer.

double-density disk.

DD disk:
Synonym for double-density disk.

data definition language.

distributed data processing.

A situation in which data processing is suspended because two or more devices or concurrent processes are each awaiting resources assigned to the other(s) or because of other mutual dependencies. For example, a situation in which a program A, with an exclusive lock on record X, asks for a lock on record Y, which is allocated to program B. Likewise, program B is waiting for exclusive control over record X before giving up control over record Y.

dead-zone unit:
A functional unit whose output analog variable is constant over a particular range of the input analog variable.

To separate the parts of blocks; for example, to remove records from a block.

To detect, to locate, and to eliminate mistakes or errors in programs.

Software designed to assist debugging.

(1) Characterized by a selection, choice, or condition that has ten possible different values or states. (2) Of a fixed-radix notation, having a radix of ten. Synonymous with denary.

decimal digit:
A digit used in the decimal system, for example, the Arabic digits 0 through 9.

decimal literal:
A numeric literal used to represent a decimal numeral.

decimal notation:
A notation that uses ten different characters, usually the decimal digits. For example, the character string 199912312359 may be construed to represent the date and time one minute before the start of the year 2000. Decimal notation is not restricted to the decimal system.

decimal numeral:
A numeral in the decimal system.

decimal numeration system:
Synonym for decimal system.

decimal point:
The radix point in the decimal system. The decimal point may be represented, according to various conventions, by a comma, by a period, or by a dot at the mid-height of the digits.

decimal system:
The fixed-radix notation that uses the ten digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9, a fixed radix of ten, and the lowest integral weight of 1. For example, in the decimal system, the numeral 576.2 represents    5 x 102 + 7 x 101 + 6 x 100 + 2 x 10-1. Synonymous with decimal numeration system.

To convert ciphertext into plaintext by means of a cryptographic system.

Synonym for decryption.

decision content:
The logarithm of the number of events in a finite set of mutually exclusive events, that is in mathematical notation:
H0 = log n
where n is the number of events.
The base of the logarithm determines the unit used. Commonly used units are:
   shannon (symbol: Sh) for logarithms of base 2,
   natural unit (symbol: nat) for logarithms of base e,
   hartley (symbol: Hart) for logarithms of base 10.
Conversion table:
1 Sh=0.693 nat=0.301 Hart
1 nat=1.433 Sh=0.434 Hart
1 Hart=3.322 Sh=2.303 nat
The decision content is independent of the probabilities of the occurrence of the events. The number of b-fold decisions needed to select a specific event out of a finite set of mutually exclusive events equals the smallest integer which is greater than or equal to the decision content defined with the logarithm of base b. This is applicable when b is an integer.
Example: Let {a,b,c} be a set of three events. Its decision content is:
H0=(log2 3) Sh=1.580 Sh
=(loge 3) nat=1.098 nat
=(log10 3) Hart=0.477 Hart

decision layer:
Synonym for output layer.

decision support system (DSS):
A computer system designed to assist users in decision-making activities. The decision support system can make use of integrated spreadsheets, artificial intelligence, computer graphics tools, and online corporate data.

decision table:
A table of conditions that are to be considered in the analysis of a problem, together with the action to be taken for each condition.

In programming, an explicit language construct that introduces one or more identifiers into a program and specifies how these identifiers are to be interpreted. In some programming languages, declarations are considered to be statements. For example, declarations of data types, storage organization, packages, or tasks.

declarative knowledge:
The knowledge represented by means of facts and rules.

declarative part:
A portion of a program that consists of one or more declarations. In COBOL, a declarative part is called "data division".

declarative region:
A portion of a program within which rules for scope and visibility are determined by corresponding declarations.

(1) In logic circuity, to convert data by reversing the effect of some previous encoding. (2) In computer security, to convert encoded text into plaintext by means of a code system.

To translate a compiled program from its machine language version into a form that may resemble the original program in high level language. A decompiled program should recompile into its original machine language version.

A software tool that decompiles programs.

To decipher or to decode.

The process of obtaining, from a ciphertext, the original corresponding data. A ciphertext may be encrypted a second time, in which case a single decryption does not produce the original plaintext. Synonymous with decipherment.

An inference that derives a logical consequence from a specific set of premises. Synonymous with deductive inference.

deductive inference:
Synonym for deduction.

deductive learning:
A learning strategy in which new knowledge is deduced from existing knowledge by means of truth-preserving transformations of assertions. Deductive learning generally leads to specialization of existing knowledge. Deductive learning includes knowledge reformulation, knowledge compilation, and other truth-preserving transformations. Synonymous with learning by deduction.

deep linking:
In hypertext systems, such as the World Wide Web, bypassing the home page and going directly to a following page.

Pertaining to an attribute, data value, or option that is assumed when none is explicitly specified. For example, in Fortran, the default naming convention specifies that names beginning with one of the letters I through N denote variables of the integer type.

default format:
A preset format that is automatically implemented unless the user specifies otherwise. Synonymous with basic format.

The lack of, or deficiency in, a characteristic essential in satisfying applicable requirements, that may affect the ability of a functional unit to perform a required function.

A process by which a data station delays its transmission when the transmission medium is busy to avoid collision with ongoing transmission.

deferred delivery service:
A service that enables an originator's user agent to request that a message being submitted be delivered not before a specified date and time.

deferred maintenance:
Maintenance that is delayed beyond the time at which it should occur according to given maintenance rules.

deferred processing:
Processing of data after being queued or postponed.

In computer vision, the clarity of detail in an image effected by a combination of resolution and contrast.

defragmentation (defrag):
The process of rearranging data on a hard drive so that data previously stored in fragments are stored together. "Defrag" is commonly used as a noun and a verb.

The delete character.

Pertaining to the task state of an executable task that is blocked by a delay statement. (Figure 58 - State transition diagram).

delay element:
Synonym for delay line.

delay line:
A device designed to introduce a desired delay in the transmission of a signal, without modifying the other characteristics of the signal. Synonymous with delay element.

delay statement:
A simple statement used to suspend execution of a task that contains a request for a delay.

A means that permits an object to assign servicing of a message to another object.

(1) In text processing, a function or mode that enables the user to remove all or part of previously entered text. (2) In data storage, to revise the storage allocation table to make available the storage space now occupied by a unit of data. Typically, deletion simply marks the storage directory without actually disturbing the data. Contrast with erase.

delete character (DEL):
A control character used primarily to obliterate an erroneous or unwanted character; on perforated tape the character is represented by a hole in each punch position.

(1) The marking of an area of a data medium as available for future use. (2) The actual change of content of an area to remove or obliterate the selected content of that area.

(1) In organization of data, one or more characters used to indicate the beginning or the end of a character string or expression. (2) In programming languages, a lexical token that indicates the beginning or the end of another lexical token or of a character string considered as a syntactic unit, such as an expression or a list of parameters. Special characters or reserved words may serve as delimiters. Contrast with separator.

In electronic mail, a transmittal step in which a message transfer agent conveys a message or report to the message store or to the user agent of a potential recipient. Delivery does not imply that a receipt by the user has taken place.

delivery notification service:
A service that enables an originator's user agent to request to be explicitly notified when a submitted message was successfully delivered to a recipient's user agent or to an access unit. Delivery does not imply that a receipt by the user has taken place. In the case of a multirecipient message, this service can be requested on a per-recipient basis.

demand paging:
The transfer of a page from external memory to real memory at the moment of need.

The process of producing a facimile of the original signal from a modulated signal.

A functional unit that recovers original data from a modulated signal.

A procedure that is invoked without being called explicitly whenever an alteration, an addition, or a deletion or other event occurs.

A device that recovers as output signals, each of the signals combined by a preceding multiplexer.

A process applied to a signal formed by multiplexing, for recovering the original independent signals, or groups of these signals. Demultiplexing may be partial, for instance, for extracting a group from a supergroup.

Synonym for decimal.

denial of service:
The prevention of authorized access to resources or the delaying of time-critical operations.

An entity relationship or an attribute relationship that denotes that the existence of one entity or attribute is of interest only if another entity or attribute, respectively, exists.

In computer graphics, the number of bits in the expression of a pixel value.

depth-first search:
A search that first picks up one of the possible branches at the highest level of the search tree and proceeds along the chosen branch to the level immediately below until the goal, a leaf (terminal node), or a predetermined depth is reached. If the goal has not been reached, the search backtracks to a previously unelvaluated branch and proceeds as before.

The range between the minimum and maximum distances from the sensor at which the focused image is acceptably shaped.

(1) To remove from a queue. (Figure 23 - Stack, queue, and double-ended list). (2) Deprecated synonym for double-ended list.

derivative action:
A series of processes required to derive a conclusion from a given set of premises.

derived type:
A data type whose data values and operations are replicas of those of an existing parent type. Strong typing prohibits operations among data values of different derived types, or between a derived type and a parent type, unless explicit type conversion is used. The set of data values or the applicable operations of derived types may be reduced or expanded. Contrast with parent type.

Data Encryption Standard.

A part of a character that extends below the writing line; for example, in certain fonts, the lower strokes of letters such as g, j, p, and q. Contrast with ascender.

In data communications, to recover the original digital signal from a scrambled digital signal.

description space:
The set of all concepts describable in the description language available to the learner.

In information retrieval, a word used to categorize or index information.

Synonym for serial-parallel converter.

design language:
A specification language with special language constructs and, sometimes, verification protocols, used to develop, analyze, and document the design of hardware or software.

design verification:
The use of formal proofs to demonstrate consistency between a formal specification of a system and a formal security policy model.

desk application:
An application program that can be run directly from a workstation to obtain office automation services; for example, an electronic calendar, a calculator, a telephone directory.

desk checking:
A static analysis technique, perhaps including manual simulation of program execution, in which source code, test results, or other documentation are visually examined, usually by the person who generated them, to identify faults, violations of development standards, or other problems.

desktop calculator:
A calculator designed primarily for use on a desk or table.

desktop computer:
A computer designed to be placed on a desk or table.

desktop publishing:
Computer-aided publishing using a microcomputer.

destructive read:
Reading that erases the data in the source location.

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