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Common Gateway Interface, Computer Graphics Interface.

Computer Graphics Metafile.

Computer Graphics Reference Model.

The material separated from a data medium when punching a hole.

chained list:
Synonym for linked list.

chain letter:
Synonym for bacterium.

chain printer:
An impact printer in which the type slugs are carried by the links of a revolving chain.

change dump:
A dump of those storage locations whose contents have changed during a specified period.

change-over system:
A temporary information processing system used to facilitate the transition from an operational system to its successor.

Synonym for jukebox.

(1) A physical or logical path along which signals may be sent; for example, an output channel. (2) In communication theory, that part of a communication system that connects the message source with the message sink. An encoder may be inserted between the message source and the input to the channel, and a decoder between the output of the channel and the message sink. Generally, these two units are not considered as being parts of the channel. In certain cases, however, they may be considered as parts of the message source and message sink, respectively. In information theory, according to Shannon, the channel can be characterized by the set of conditional probabilities of occurrence of all the messages received at the message sink when a given message emanates from the message source. (3) In hypermedia and multimedia, a logical space through which runtime objects are presented to the user. Channels are assigned to physical devices such as graphic windows or loudspeakers for making the runtime objects perceivable to the user. (4) Synonym for transmission channel.

channel capacity:
The measure of the ability of a given channel, subject to specific constraints, to transmit messages from a specified message source expressed as the maximum bit rate which can be achieved with an arbitrary small probability of errors by use of an appropriate code.

A member of a predefined set of elements that is used for the representation, organization, or control of data. Characters are sometimes categorized as shown in the figure. (Figure 12 - Character taxonomy).

character average information content:
Synonym for character mean entropy.

character box:
An imaginary parallelogram on a display or a printing medium that contains all parts of one graphic character. Character boxes may overlap to adjust the spacing between characters or to make adjacent characters touch.

character display:
Synonym for character display device.

character display device:
A display device that provides a representation of data only in the form of graphic characters. Synonymous with character display.

character fill:
To insert as often as necessary into a data medium the representation of a specified character; character fill is sometimes used to obliterate unwanted data.

character generator:
A functional unit that converts the code value of a character into the graphic representation of the character for display.

(1) Of a logarithm, the integer part, which may be positive or negative, of the representation of a logarithm. (2) The numeral that internally represents the exponent in a floating-point representation. The characteristic may differ from the exponent in a floating-point representation by a constant; for example, if the exponent is -3 and the constant is 64, the characteristic will be 61.

characteristic description:
A concept description that states properties common to instances of a given concept.

character information rate:
Synonym for character mean entropy.

character literal:
A literal that consists of one character. Character literals usually are enclosed within delimiters to distinguish them from other lexical tokens. Programming languages usually employ different delimiters for character literals and string literals. A character literal may be a string literal of length one. Contrast with string literal.

character mean entropy:
The mean per character of the entropy for all possible messages from a stationary message source, defined in mathematical notation by the limit:
H '   =   lim  Hm / m
where Hm is the entropy of the set of all sequences of m characters from the source. The character mean entropy may be expressed in a unit such as the shannon per character. The limit may not exist if the source is not stationary. Synonymous with character mean information content, character average information content, character information rate.

character mean information content:
Synonym for character mean entropy.

character mean transinformation content:
The mean per character of the mean transinformation content for all possible messages from a stationary message source, defined in mathematical notation by the limit:
T '   =   lim  Tm / m
where: Tm is the mean transinformation content for all pairs of corresponding to input and output sequences of m characters each. The character mean transinformation content may be expressed in a unit such as the shannon per character.

character-oriented protocol:
A data link protocol in which both user data and data link control functions are coded as specific characters, for example, a basic mode link control protocol.

character outline:
The graphic pattern established by the stroke edges of a character.

character printer:
A printer that prints a single character at a time. Contrast with line printer.

character reader:
An input unit that performs character recognition.

character recognition:
The identification of characters by automatic means.

character set:
A finite set of characters that is complete for a given purpose; for example, ASCII.

character spacing reference line:
In character recognition, a line that is used to evaluate the horizontal spacing of characters. It may be a line that equally divides the distance between the sides of a character box.

character string:
A string consisting solely of characters. Contrast with string literal.

character type:
An ordinal type, whose values represent characters.

A computer conference in which participants exchange information in real-time.

chat group:
In a chat, a group of users conversing on a given subject.

chat room:
A virtual meeting place where a chat takes place.

check bit:
A binary accuracy control character, for example a parity bit.

checking program:
A diagnostic program that examines source programs or data for incorrect syntax, semantics, or lack of conformity to specified requirements.

A processing juncture, at which the normal operation of a program or system is momentarily suspended in order to determine its environmental status.

checkpoint dump:
A dump that records the environment at a checkpoint.

In computer vision, a blob that is wholly surrounded by another blob. Example: The white cross of the flag of Switzerland is the child of the red part.

(1) A minute piece of semiconductive material used in the manufacture of electronic components. (2) An integrated circuit on a piece of semiconductive material. (3) Loosely, an integrated circuit. (4) In micrographics, a piece of microfilm that is smaller than a microfiche and that contains microimages and coded identification.

chip card:
Synonym for smart card.

choice device:
An input unit that provides one value to be selected from a set of alternatives; for example, a function keyboard.

chosen-plaintext attack:
In computer security, an analytical attack in which the cryptanalyst can submit an unlimited number of plaintext messages and examine the corresponding ciphertext.

Combining two video signals that are in sync, such that the combined signal is the second signal whenever the first is of some specified color, called the chroma-key color, and is the first signal otherwise. Example: A weatherman stands in front of a blue background, but at home, the TV viewer sees the weather map in place of the background color, with the weatherman superimposed.

chroma signal:
A signal that conveys chrominance information.

The hue and saturation of a color. Chrominance does not include the luminance.

Grouping of data into a single entity at a higher conceptual level for further analysis or for storage and retrieval.

computer-integrated manufacturing, computer input microfilm, corporate information management.

cipher system:
Synonym for cryptographic system.

Data produced through the use of encryption, the semantic content of which is not available without the use of cryptographic techniques.

ciphertext-only attack:
An analytical attack in which the cryptanalyst possesses only the ciphertext.

An interconnection of electrical, optical, or logical elements that can perform one or more functions.

circuit switching:
A process that, on demand, connects two or more data terminal equipment and permits the exclusive use of a data circuit between them until the connection is released. Contrast with message switching, packet switching.

circular list:
A linked list which, following the processing of all items from any starting point, returns to the item preceding the starting point. Synonymous with ring.

circular shift:
A logical shift in which the characters moved out of one end of a computer word or register are reentered into the other end. Synonymous with end-around shift.

circulating register:
A shift register in which data moved out of one end of the register are reentered into the other end, as in a closed loop.

circulating storage:
Dynamic storage involving a closed loop. Synonymous with cyclic storage.

complex-instruction-set computer.

CISC processor:
A processor that employs powerful, often elaborate, machine instructions, to reduce the number of instructions executed. Because of the instruction complexity, each can take several clock cycles to execute. Synonymous with complex instruction set computer processor. Contrast with reduced instruction set computer processor.

Clark-Wilson integrity model:
An example of a computer security model.

(1) In object-oriented design or programming, a group of objects that share a common definition and that, therefore, share common properties, operations, and behavior. Members of the group are called instances of the class. (2) In a conceptual schema language, all possible entities in the universe of discourse for which a given proposition holds. (3) In programming languages, a template for objects that defines the internal structure and the set of operations for instances of such objects. In this usage, the concept of class is an extension of the concept of data type.

Abridged term for security classification.

To cause one or more storage locations to be set in a prescribed state, usually the state corresponding to zero or the state corresponding to the space character. Contrast with sanitizing.

clear all function:
The function that allows the cancellation of data in the working registers and storage devices.

Synonym for security clearance.

clear area:
In character recognition, a specified area that is to be kept free of printing or any other markings not related to machine reading.

clear entry function:
The function that allows the cancellation of data entered into the calculator but not yet processed.

In computer security, overwriting classified data on a data medium that has a particular security classification and security category, so that this data medium may be reused for writing at the same security classification and security category.

clear memory function:
The function that allows the cancellation of data in the storage devices to which the keys refer. There may be other "clear" keys on the calculator used to cancel specified functions.

Synonym for plaintext.

To press and release a pushbutton on a pointing device to select the area or the display element indicated by the pointer.

click data:
Data obtained by counting, and possibly the identity of, who has clicked on a banner or some other particular link.

click through:
The access of a new Web page based on clicking on a banner.

A functional unit that receives services from a server. Services may be dedicated services or shared services.

In distributed data processing, pertaining to a method of distributed processing in which a client obtains services from a server.

clip art:
Electronic artwork, usually provided in a software library.

A storage area for temporarily holding text or graphics for reuse in the same or a different document.

clip mask:
A region, defined by either a pixel map or a list of rectangles, outside whose boundary the displayed data are truncated.

The action of truncating data or a display image by removing all the display elements that lie outside a clip mask.

The electronic component in an electronic device that generates a steady stream of regularly spaced pulses. A clock is generally used for regulating the time of state transitions, synchronizing multiple events, or measuring time intervals inside the electronic device.

clock calendar:
Synonym for time-of-day clock.

clock rate:
The pulse rate of the output of the clock. The clock rate is given in hertz (Hz), kilohertz (kHz), megahertz (MHz), or gigahertz (GHz). Synonymous with clock speed.

clock register:
Synonym for timer.

clock speed:
Synonym for clock rate.

clock track:
A track on which a pattern of signals is recorded to provide timing references.

closed guard:
A guard whose condition evaluates to FALSE.

closed security environment:
An environment in which special attention is paid (in the form of authorizations, security clearances, configuration controls, etc.) to protect data and resources from accidental or malicious acts.

closed subroutine:
A subroutine, that needs only to be linked by a call for use at more than one place in a program.

closed system:
A system whose characteristics comply with proprietary standards. Contrast with open system.

closed user group (CUG):
A group of specified users of a data network that is assigned a user facility that permits them to communicate with each other but precludes access to or from all other users of the data network. A user data terminal equipment may belong to more than one closed user group.

clue conflict:
The situation that arises when the body interprets sensations from multiple sources resulting in information that is inconsistent. Extreme cases of clue conflict may cause nausea.

In distributed data processing, a set of functional units under common control.

cluster analysis:
The process of handling adjacent pixels within a given color or a given gray level as a unit.

common management information service.

computer numerical control.

coaxial cable:
A cable containing one or more coaxial pairs.

coaxial pair:
A transmission medium that consists of two cylindrical conductors, one within the other, that share the same axis.

A general-purpose, high-level, procedure-oriented language intended for the solution of problems in business data processing. The name is derived from COmmon Business-Oriented Language.

COnference on DAta SYstems Languages.

CODASYL model:
In a database management system, a network model whose pattern of organization is based on set types that specify associations among record types.

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