CD ROM XAAbbreviation for compact disc read only memory eXtended architecture. An extension of the CD-ROM standard, billed as a hybrid of CD ROM and CD-IS formats.
CD-iAbbreviation for compact disc-interactive. A compact disc format that provides audio, digital data, still graphics, and limited motion video, and that…
CD-ROMSee Compact Disc. (Compact Disk - Read Only Memory) Data storage medium that uses compact discs to store about 1,500 floppy discs worth of data.
CDMA (Code-division multiple access access)a digital cellular technology that uses spread-spectrum techniques. Unlike competing systems, such as GSM, that use TDMA, CDMA does not assign a specific…
CDPSKAbbreviation for coherent differential phase-shift keying.
CDRAbbreviation for complementarity-determining regions.
CEIAbbreviation for comparably efficient interconnection.
CellThe fundamental level of structural organization in complex organisms. Eukaryotic cells contain a nucleus (with chromosome s) and cytoplasm with the…
cell delay variationA quantification of variability in cell delay for an asynchronous transfer mode (ATM) layer connection. [T1.630-1999]
cell delineationThe identification of the asynchronous transfer mode (ATM) cell boundaries within a cell stream. [T1.646-1995]
cell headerAsynchronous transfer mode (ATM) layer protocol control information that precedes user data. [After T1.627-1993]
cell loss ratio1. In a network, the ratio (1- x/y), where: y is the number of cells that arrive in an interval at the ingress of the network; and x is the number of…
cell relayA statistically multiplexed interface protocol for packet switched data communications that uses fixed-length packets, i.e., cells, to transport data.
cellularRefers to communications systems, especially the Advance Mobile Phone Service (AMPS), that divide a geographic region into sections, called cells.
cellular mobileA mobile communications system that uses a combination of radio transmission and conventional telephone switching to permit telephone communication to and…
cellular technologyIn telephony, a generic term for all wireless phones, regardless of the technology they use; the term derives from cellular base stations that receive and…
center frequencyIn frequency modulation, the rest frequency, i.e., the frequency of the unmodulated carrier. Synonym carrier frequency. 2.
central office (C.O.)A common carrier switching center in which trunks and/or loops are terminated and switched.
Central Office (CO) CodeThe sub-NPA code in a TN, i.e., digits D-E-F of a 10-digit NANP Area address. Central office codes are in the form "NXX," where N is a number from 2 to 9…
central office connecting facilityLoosely, in the sense of a trunk between public and private switches, a synonym for central office trunk. See trunk.
central office prefixThe first three digits (N) of the seven-digit telephone number assigned to a customer's telephone exchange service when dialed on a local basis.
central office trunkLoosely, in the sense of a trunk between public and private switches, a synonym for central office connecting facility. See trunk.
Central Processing UnitThe Central Processing Unit (CPU) is the heart of a computer as it is the part that contains the computer's ability to obey instructions.
centralized attendant services (CAS)A function of a usually centrally located attendant console that permits the control of multiple switches, some of which may be geographically remote.
centralized automatic message accounting (CAMA)An automatic message accounting system that serves more than one switch from a central location. Note: When using CAMA, human intervention may be required.
centralized operationOperation of a communication network in which transmission may occur between the control station and any tributary station, but not between tributary…
centralized ordering group (COG)An organization provided by some communications service providers to coordinate services between the companies and vendors.
Centrex® (CTX) serviceA service offered by Bell Operating Companies that provides functions and features comparable to those provided by a PBX or a PABX. Note: "Centrex® C.O.
certificateDigital signature combining data verification and encryption key. See PKI Digital Signature.
certificate holdIn cryptography, an order suspending the use of a certificate. Note: A certificate hold is a security procedure that is analogous to placing a hold on a…
certificate informationIn cryptography, the information in a certificate which is signed. [After X9.57]
certificate management[The] process whereby certificates . . . are generated, stored, protected, transferred, loaded, used, and destroyed. [INFOSEC-99]
certificate serial numberIn cryptography, an integer value that is (a) unique within the issuing certificate authority (CA), and (b) unambiguously associated with a certificate…
certificate userIn cryptography, a station, agency, or individual user that needs to know, with certitude, the public key of another entity. [After X.509]
CertificationCertification means the approval by a certifying official that a labor condition application is complete and does not contain obvious inaccuracies.
Certification AgentThe individual, group, or organization responsible for conducting a security certification.
certification authority (CA)In cryptography, a center trusted by one or more agencies or individuals to create and assign certificates and, optionally, to create user's keys.
certification pathIn cryptography, the ordered sequence of entity certificates that can be processed, with the public key of the initial entity in the path, to determine…
certified identityAn identity in the form of an attribute in a certificate. The issuing authority will have authenticated the owner of the certificate [ECMA138].
certified network engineerIn computer networking, one who has met proprietary training and certification requirements pertinent to network design or maintenance.
CertifierPerson responsible for certification of a system and/or product [CESG]
cesium clockA clock containing a cesium standard as a frequency-determining element.
cesium standardA primary frequency standard in which electronic transitions between the two hyperfine ground states of cesium-133 atoms control the output frequency.
CGIAbbreviation for common gateway interface. A means for allowing programs or scripts (usually written in C++ or Perl) to add functionality to the World…
cgmAbbreviation for computer graphics metafile. A digital file format (standard) used for the storage or transmission of digital representations of graphics…
challenge and reply authentication[A] prearranged procedure in which a subject requests authentication of another, and the latter establishes validity with a correct reply. [INFOSEC-99]
change backThe procedure of transferring signaling traffic from alternative signaling link(s) to the signaling link which has become available as a result of having…
changeoverThe procedure of transferring signaling traffic from one signaling link to one or more different signaling links, when the link in use fails or is…
ChannelThe bed of a stream or river. This can also refer to a submerged stream or river channel in a reservoir.
channel bankThe part of a carrier-multiplex terminal that performs the first step of modulation by multiplexing a group of channels into a higher bandwidth analog…
channel bitsBinary data transmitted over a communications link. Note: Channel bits are derived from user information by FEC (forward error correction) coding and…
channel capacity1. The maximum possible information transfer rate through a channel, subject to specified constraints. 2.
channel gateA device for connecting a channel to a highway, or a highway to a channel, at specified times.
channel noise levelThe ratio of the channel noise at any point in a transmission system to an arbitrary level chosen as a reference.
channel offsetThe constant frequency difference between a channel frequency and a reference frequency which may frequency hop.
channel packingMaximizing the use of voice frequency channels for data transmission by multiplexing a number of channels of lower data rate into a single voice frequency…
channel reliability (ChR)The percentage of time a channel was available for use in a specified period of scheduled availability.
channel service unit (CSU)A line bridging device that (a) is used to perform loop-back testing, (b) may perform bit stuffing, (c) may also provide a framing and formatting pattern…
channel time slotA time slot that starts at a particular instant in a frame and is allocated to a channel for transmitting data, such as a character or an in-slot signal.
channel-associated signalingSignaling in which the signals necessary to switch a given circuit are transmitted via the circuit itself or via a signaling channel permanently…
channelingAn application of push technology that allows users to automatically receive specific kinds of content. [Bahorsky]
ChannelizationThe modification of a natural river channel; may include deepening, widening, or straightening.
character checkA method of error detection using the preset rules for the formulation of characters.
character filterSoftware that is capable of selectively removing characters from a data stream, e.g.
character generatorA functional unit that converts the coded representation of a character into the graphic representation of the character for display.
character integrityPreservation of a character during processing, storage, and transmission.
character intervalIn a communications system, the total number of unit intervals required to transmit any given character, including synchronizing, information, error…
character setA grouping of alphabetic, numeric, and other characters that have some relationship in common.
character-count integrityThe preservation of the exact number of characters that are originated in a message in the case of message communications, or per unit time, in the case…
character-steppedPertaining to control of start-stop teletypewriter equipment in which a device is stepped one character at a time.
characteristic distortionIn telegraphy, the distortion caused by transients that, as a result of previous modulation, are present in the transmission channel.
characteristic frequencyA frequency which can be easily identified and measured in a given emission. A carrier frequency may, for example, be designated as the characteristic…
characteristic impedance (Zo)The impedance of a circuit that, when connected to the output terminals of a uniform transmission line of arbitrary length, causes the line to appear…
charging reference locationIn Universal Personal Telecommunications Service, the geographical location that may be used by the UPT service providers to determine the…
ChatSee Instant messaging (IM). A form of real-time communication between two or more people based on typed text.