1. Loosely, the group of microwave frequencies from 4 GHz to 6 GHz used in satellite communications.
2. The band of satellite downlink frequencies between
3. 7 and
4. 2 GHz.
Note 1: For federal procurement purposes, the radio frequency band(s) must be specified using the upper and lower limits of the band, per 47 CFR
30
0.
Note 2:… (Read More →)

Abbreviation for communications-electronics.

A general-purpose, high-level, structured computer programming language.
Note: C-language was originally designed for and implemented on the UNIXTM operating system.

The term "C-Message Noise" denotes the frequency weighted average noise within an idle voice channel. The frequency weighting, called C-message, is used to simulate the frequency characteristic of the 5OO-type telephone set and the hearing of the average subscriber.

A noise spectral weighting used in a noise power measuring set to measure noise power on a line that is terminated by a 500-type set or similar instrument.
Note: The instrument is calibrated in dBrnC.

The term "C-Notched Noise" denotes the C-message frequency weighted noise on a voice channel with a holding tone, which is removed at the measuring end through a notch (very narrow band) filter.

Abbreviation for central office.

Abbreviation for carrier-to-receiver noise density.

Carrier to Noise Density Ratio

Abbreviation for command and control warfare.

Carrier Aggregation

1. An assembly of one or more insulated conductors, or optical fibers, or a combination of both, within an enveloping jacket.
Note 1: A cable is constructed so that the conductors or fibers may be used singly or in groups.
Note 2: Certain types of communications cables, especially long submarine cables but also terrestrial cables, whether the communications media are… (Read More →)

A cable that is ready for installation in specific applications and usually terminated with connectors.

For a cabled single-mode optical fiber under specified length, bend, and deployment conditions, the wavelength at which the fiber's second order mode is attenuated a measurable amount when compared to a multimode reference fiber or to a tightly bent single-mode fiber.

The ratio of cable conductor or cable pair kilometers in use to total cable conductor or cable pair kilometers available in the plant, e.g., the ratio of revenue producing cable pair kilometers in use to total cable pair kilometers in plant. [47 CFR Pt.36-A]

Synonym [in cable television] headend.

See sheath.

In CATV systems, a bidirectional high-speed digital communications interface, located on a subscriber's or user's premises, and used, for example, for Internet access or other digital communications.

A fixed or mobile station used for the transmission of television and related audio signals, signals of standard and FM broadcast stations, signals of instructional television fixed stations, and cablecasting from the point of reception to a terminal point from which the signals are distributed to the public. [47CFR]

A broadband communications technology in which multiple television channels, as well as audio and data signals, may be transmitted either one way or bidirectionally through an often hybrid (fiber and coaxial) distribution system to a single or to multiple specific locations. CATV originated in areas where good reception of direct broadcast TV was not possible. Now CATV also consists of… (Read More →)

1. Carrier Access Code,
2. Customer Administration Center,
3. Connection Admission Control

A buffer, smaller and faster than main storage, used to hold a copy of instructions and data in main storage that are likely to be needed next by the processor and that have been obtained automatically from main storage.

Abbreviation for computer-aided design.

Communications Assistance for Law Enforcement Act

1. In communications, any demand to set up a connection.
2. A unit of traffic measurement.
3. The actions performed by a call originator.
4. The operations required to establish, maintain, and release a connection.
5. To use a connection between two stations.
6. The action of bringing a computer program, a routine, or a subroutine into effect, usually by… (Read More →)

See abandoned call.

The mechanism that allows a user to be alerted on one terminal and to choose to answer the call on any terminal, not necessarily the one through which alerting took place. [T
1. Rpt34-1994]

A call control signal sent by the called terminal to indicate that it accepts the incoming call.

The Call Agent provides call processing, call control, feature control and Operations Administration Maintenance & Provisioning to manage services for a packet network comprised of multiple types of media gateway endpoints. The network itself may transport traffic over many types of packet switching fabric, such as IP, Ethernet, ATM or Frame Relay. The Media Gateways (i.e., Access and Trunk Gateways)… (Read More →)

Signaling required for supervision of a bearer service between two end points, including support for the functions of call origination, call delivery, and handover.

In a telecommunications system, a demand by a user for a connection to another user.
Note: In telephone traffic analysis, call attempts are counted during a specific time frame. The call-attempt count includes all completed, overflowed, abandoned, and lost calls.

[The] procedure for identifying and authenticating a remote information-systems (IS) terminal, whereby the host system disconnects the terminal and reestablishes contact. [INFOSEC-99] Synonym dial back.

1. The contention that occurs when a terminal and data circuit-terminating equipment (DCE) specify the same channel at the same time to transfer a call request and handle an incoming call.
Note: When call collision occurs, the DCE proceeds with the call request and cancels the incoming call.
2. The condition that occurs when a trunk or channel is seized… (Read More →)

The ratio of successfully completed calls to the total number of attempted calls.
Note: This ratio is typically expressed as either a percentage or a decimal fraction.

One of a set of control characters used in call-control signaling.
Note: The signals representing call control characters may be used under defined conditions on interchange circuits other than the originating circuit.

The network intelligence that provides call/connection processing and control. [T1.667-1999]

A member of the set of network management signals used to establish, maintain, or release a call.

The logical link between the device performing an electronic surveillance access function and the LEA (law enforcement agency) that primarily carries call-identifying information. [T1.260-1998]

1. The delay that occurs when a call arrives at an automatic switching device and no channel or facility is immediately available to process the call.
2. The time between the instant a system receives a call attempt and the instant of initiation of ringing at the call receiver end instrument.

A service feature in which call data on a specific telephone extension or group of subscribers are collected and recorded for cost-of-service accounting purposes.

1. The time between (a) the instant a connection, i.e., off-hook condition at each end, is established between the call originator and the call receiver and (b) the instant the call originator or the call receiver terminates the call.
2. In data transmission, the duration of the information transfer phase of an information transfer transaction.

A service feature, available in some switching systems, whereby calls can be rerouted automatically from one line, i.e., station number, to another or to an attendant.
Note: Call forwarding may be implemented in many forms.

CG is a code control that regulates the maximum rate at which calls are released toward a destination code. Equipment vendors commonly provide the capability to Call Gap at intervals of
0. 10 to 600 seconds on a range of numbers from three (3), six (6), or seven (7), through ten (10) digits.

A service feature in which a user may retain an existing call while accepting or originating another call using the same end instrument.

A network utility that consists of a name assigned by the originating network for each established or partially established virtual call.
Note: When a call identifier is used in conjunction with the calling data terminal equipment (DTE) address, the call identifier uniquely identifies the virtual call.

Synonym traffic intensity.

1. In telegraphy, route selection, signaling, and circuit usage and availability for a call.
2. In universal personal telecommunications, the ability of a user to inform the network how to handle incoming calls in accord with certain parameters, such as the call originator, the time of day, and the nature of the call.
Note: Call management is accomplished by means… (Read More →)

An entity, such as a person, equipment, or program that originates a call. Synonym calling party.

A service feature of some switching systems enabling a user, by dialing a predetermined code, to answer incoming calls that are directed to another user in a preselected call group.

1. The sequence of operations performed by a switching system from the acceptance of an incoming call through the final disposition of the call.
2. The end-to-end sequence of operations performed by a network from the instant a call attempt is initiated until the instant the call release is completed.
3. In data transmission, the operations required to complete all… (Read More →)

1. A call control signal transmitted by the called data circuit-terminating equipment (DCE) to the calling data terminal equipment (DTE) to report (a) the progress of a call by using a positive call progress signal or (b) the reason why a connection could not be established by using a negative call progress signal.
2. A voiceband tone that is applied… (Read More →)

An audible signal returned by a network to a call originator to indicate the status of a call.
Note: Examples of call progress tones include dial tones and busy signals.

An entity, such as a person, equipment, or program to which a call is directed. Synonym called party.

Recorded data pertaining to a single call.

In communication systems, the time interval from initiation of a clearing signal by a terminal until the available-line condition appears on originating terminal equipment.

A switching system service feature that prevents selected terminals from exercising one or more service features otherwise available from the switching system.

A specific portion of the processing of a call. [T1.667-1999]

The ratio of total call attempts that result in call set-up error to the total call attempts in a population of interest. [T1.504-1989]

The ratio of total call attempts that result in call set-up failure to the total call attempts in a population of interest. [T1.504-1989]

1. The overall length of time required to establish a circuit-switched call between users.
2. For data communication, the overall length of time required to establish a circuit-switched call between terminals; i.e., the time from the initiation of a call request to the beginning of the call message.
Note: Call set-up time is the summation of: (a) call request time--the… (Read More →)

A station or address designator represented by a combination of characters or pronounceable words that is used to identify such entities as a communications facility, station, command, authority, activity, or unit.

In common-channel signaling, the effect on a traffic circuit of the arrival at a switching center of an abnormally delayed call control signal relating to a previous call, while a subsequent call is being set up on the circuit.

A switching system service feature that allows a switch attendant to talk privately in either direction on an established call.

The call through test confirms capabilities of the interface relative to an actual or simulated call: Basic call set-up; sequential, acknowledged transmission of user data; and call termination.

A procedure that permits an entitled user to be informed about the routing of data for an established connection, identifying the entire route from the origin to the destination.
Note: There are two types of call tracing. Permanent call tracing permits tracing of all calls. On-demand call tracing permits tracing, upon request, of a specific call, provided that the called… (Read More →)

A switching system service feature that allows the calling or called user to instruct the local switching equipment or switch attendant to transfer an existing call to another terminal.
Note: Call transfer may be available on a call-by-call basis or on a semipermanent basis.

In telephony, a service feature that provides an indication to a terminal already engaged in an established call that one or more calls are awaiting connection.

A signal sent in the backward direction indicating that a call cannot be completed because of a time-out, a fault, or a condition that does not correspond to any other particular signal.

A call control signal sent by the called terminal to indicate that it does not accept the incoming call.

A call state during which the network establishes a communications path between the caller and the public safety answering point (PSAP) customer installation (CI). [T1.414-1998]

In the establishment of a connection or in the call setup, i.e., placement of a call, the time from the initiation of a calling signal to the receipt of a proceed-to-select signal--such as a dial tone--by the call originator.

A unit used to measure communications traffic.
Note 1: A call-second is equivalent to 1 call 1 second long.
Note 2: One user making two 75-second calls is equivalent to two users each making one 75-second call. Each case produces 150 call-seconds of traffic.
Note 3: The CCS, equivalent to 100 call-seconds, is often used.
Note 4: 3600 call-seconds =… (Read More →)

In the establishment of a connection or the placement of a call, the time from the receipt by the call originator of a proceed-to-select signal (dial tone), until all the selection signals have been transmitted (dialing has been completed).

The table of allocation of international call sign series contained in the current edition of the International Telecommunication Union (ITU) Radio Regulations.
Note: In the table of allocation, the first two characters of each call sign (whether two letters or one number and one letter, in that order) identify the nationality of the station. In certain instances where the complete… (Read More →)

Synonym call receiver.

A network-provided service feature in which the network notifies a calling terminal of the address to which the call has been connected.

A sequence of characters transmitted to the calling terminal to permit identification of the called line.

A communication system service feature that enables the system to complete an access attempt in spite of issuance of a user blocking signal.
Note: Systems that provide this feature monitor the busy user until the user blocking signal ends, and then proceed to complete the requested access. This feature permits holding an incoming call until the called party is free.

A network service feature that permits the recipient of an incoming call to determine, even before answering, the number from which the incoming call is being placed.

See caller ID.

The number used to identify the calling terminal within the context of the emergency service call. [T1.414-1998]

A radio frequency that a station uses to call another station.

At a minimum, the calling line identification includes a single calling party number; it may also include a second calling party number, a calling party subaddress, and redirecting number information. Calling line identification may not include any calling party number due to interworking, or because of an interaction with the CLIR supplementary service. [T1.625-1993]

Synonym call originator.

A set of digits and related indicators (type of number, numbering, plan identification, screening indicator, presentation indicator) that provide numbering information related to the calling party. [T1.625-1993]

The number of telephone calls originated during a specified time interval such as one hour.

A sequence of instructions together with any associated data necessary to perform a call.

A call control signal transmitted over a circuit to indicate that a connection is desired.

A network-provided service feature in which the network notifies a called terminal of the address from which the call has originated.

A sequence of characters transmitted to the called terminal to permit identification of the calling line.

A service feature that enables the system to complete an access attempt in spite of temporary unavailability of system transmission or switching facilities required to establish the requested access.
Note: Systems that provide calling party camp-on monitor the system facilities until the necessary facilities become available, and then proceed to complete the requested access. Such systems may or may not… (Read More →)

A service feature that permits a terminal either to make outgoing calls or to receive incoming calls, but not both.

Acronym for centralized automatic message accounting.

A combination of camera and video tape recorder in one device.
Note: Camcorders permit easy and rapid photography and recording simultaneously. Camcorders are available in most home video formats: 8mm, Hi-8, VHS, VHS-C, S-VHS, etc. [After Silicon]

See automatic callback, called-party camp-on, queue traffic.

1. A signal that informs a busy telephone user that another call originator is waiting for a connection.
2. A teleprinter exchange facility signal that automatically causes a calling station to retry the call-receiver number after a given interval when the call-receiver teleprinter is occupied or the circuits are busy. Synonym speed-up tone.

A camp-on with the release of the call-originator terminal until the called-receiver terminal becomes free.
Note: The call originator can thus establish other calls until the recall signal is obtained, rather than simply wait until the call-receiver line is available.

Abbreviation for cancel character.

An independent, nongovernment, not-for-profit association for the development, by consensus, of Canadian standards and product certification.

1. A control character used by some conventions to indicate that the data with which it is associated are in error or are to be disregarded.
2. An accuracy control character used to indicate that the data with which it is associated are in error, are to be disregarded, or cannot be represented on a particular device.

CANT is a trunk group control that allows traffic to be canceled before hunting for a circuit to a destination. Equipment vendors commonly provide the capability to implement this control on a percentage basis.

The luminous intensity in a specified direction, of a monochromatic source which has a frequency of 540 x 1012 Hz and which has a radiant intensity, in the specified direction, of (1/683) watt per steradian.

A domain name of an Internet resource indicating its type or its capabilities.
Note: One Internet resource may have a set of different domain names, one of which is the preferred one. Example: www. isi. edu denotes a host containing a Web server. [2382-pt.35]

Common Alerting Protocol

1. A token allowing its holder an access right.
Note: Capability-based systems (e. g. PIDs) provide added value in authentication but, since they are not cryptographically secure, cannot replace the password system [CESG].
2. As used in the context of security, a form of privilege attribute. It is a token (recognized by a process managing access to security objects) possession… (Read More →)

Synonym alias point code.

The transfer of energy from one circuit to another by means of the mutual capacitance between the circuits.
Note 1: The coupling may be deliberate or inadvertent.
Note 2: Capacitive coupling favors transfer of the higher frequency components of a signal, whereas inductive coupling favors lower frequency components, and conductive coupling favors neither higher nor lower frequency components.

See channel capacity, traffic capacity.

Capital Expenditure

A phenomenon, associated with FM reception, in which only the stronger of two signals at or near the same frequency will be demodulated.
Note 1: The complete suppression of the weaker signal occurs at the receiver limiter, where it is treated as noise and rejected.
Note 2: When both signals are nearly equal in strength, or are fading independently, the… (Read More →)

In telephone-service security, a link between the card and a terminal starting with the answer to reset (ATR) and ending with a subsequent reset or a deactivation of the card. [T1.707-1998]

The validating process that Includes, but is not limited to, ensuring that a telecommunications charge card has been assigned by the card issuer and that the personal identification number matches the one assigned to that account.

Eight imaginary straight lines extending radially on the ground from an antenna location in the following azimuths with respect to true North: 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°. [47CFR]
Note: The four radials at 0°, 90°, 180°, and 270° of azimuth with respect to true North are referred to as the cardinal points. The cardinal points are equivalent… (Read More →)

In a frequency stabilized system, the sinusoidal component of a modulated wave whose frequency is independent of the modulating wave; or the output of a transmitter when the modulating wave is made zero; or a wave generated at a point in the transmitting system and subsequently modulated by the signal; or a wave generated locally at the receiving terminal which… (Read More →)

1. A wave suitable for modulation by an information-bearing signal.
2. An unmodulated emission.
Note: The carrier is usually a sinusoidal wave or a uniform or predictable series of pulses. Synonym carrier wave.
3. Sometimes employed as a synonym for carrier system.

A code (dialed by the user) to select a specific service provided by the entity to which the code is assigned by the NANPA (North American Numbering Plan Administration); the code used is either 10xxx or 101xxxX where the Xs represent the 3- or 4-digit code that was assigned. The originating switch uses the code to route the call to… (Read More →)

A short-duration loss of carrier signal.

A transmission facility that provides several communication channels over a single bidirectional path. A carrier facility system generally consists of multiplex function at two terminal locations and an interconnecting path consisting of: (1) a higher-level facility system; (2) a facility assembly; or (3) combinations of carrier facility systems and facility assemblies.

1. The nominal frequency of a carrier wave.
2. In frequency modulation, synonym center frequency.
3. The frequency of the unmodulated electrical wave at the output of an amplitude modulated (AM), frequency modulated (FM), or phase modulated (PM) transmitter. [47CFR]
4. The output of a transmitter when the modulating wave is made zero. [47CFR]

1. A numeric code assigned by the North American Numbering Plan (NANP) Administrator for the provisioning of selected switched services. The numeric code is unique to each entity and is used by the telephone company to route the call to the trunk group designated by the entity to which the code was assigned. [FCC]
2. A 4-digit code that controls… (Read More →)

The carrier remaining after carrier suppression in a suppressed carrier transmission system.
Note: Sometimes the residual carrier is used to provide the reference for an automatic frequency control system.

The level of a carrier signal at a specified point in a communications system.
Note: The carrier level is usually expressed in dB relative to a specified reference level.

See frequency-division multiplexing.

The noise level resulting from undesired variations of a carrier in the absence of any intended modulation. Synonym residual modulation.

1. The average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle taken under the condition of no modulation. [NTIA] [RR]
Note: The concept does not apply to pulse modulation or frequency-shift keying.
2. The average unmodulated power supplied to a transmission line.

A code that identifies whether the caller dialed the elected or chosen carrier and whether the caller presubscribed to the elected or chosen carrier. [T1.667-1999]

In a local area network, an ongoing activity of a data station to detect whether another station is transmitting.

A network control scheme in which a node verifies the absence of other traffic before transmitting.

A network control protocol in which (a) a carrier sensing scheme is used, (b) a data station that intends to transmit sends a jam signal, (c) after waiting a sufficient time for all stations to receive the jam signal, the data station transmits a frame, and (d) while transmitting, if the data station detects a jam signal from another station,… (Read More →)

A network control protocol in which (a) a carrier sensing scheme is used and (b) a transmitting data station that detects another signal while transmitting a frame, stops transmitting that frame, transmits a jam signal, and then waits for a random time interval before trying to send that frame again.

1. In the transmission of binary or teletypewriter signals, keying in which the carrier frequency is shifted in one direction for marking signals and in the opposite direction for spacing signals.
2. In amplitude modulation, a condition that results from imperfect modulation in which the positive and negative excursions of the modulating envelope are unequal in amplitude.
Note 1: The… (Read More →)

See suppressed carrier transmission.

In a radio receiver, the generation of a reference carrier with a phase closely matching that of a received signal.

A multichannel telecommunications system in which a number of individual circuits (data, voice, or combination thereof) are multiplexed for transmission between nodes of a network.
Note 1: In carrier systems, many different forms of multiplexing may be used, such as time-division multiplexing and frequency-division multiplexing.
Note 2: Multiple layers of multiplexing may ultimately be performed upon a given input signal;… (Read More →)

Synonym carrier (cxr).

In radio receivers, the ratio of the level of the carrier to that of the noise in the intermediate frequency (IF) band before any nonlinear process, such as amplitude limitation and detection, takes place.
Note: The CNR is usually expressed in dB.

In satellite communications, the ratio of the received carrier power to the receiver noise power density.
Note 1: The carrier-to-receiver noise density ratio is usually expressed in dB.
Note 2: The carrier-to-receiver noise density is given by C/kT, where C is the received carrier power in watts, k is Boltzmann's constant in joules per kelvin, and T is the receiver… (Read More →)

Acronym for cable television relay service (CARS) station.

A rule defining the approximate bandwidth requirements of communications system components for a carrier signal that is frequency modulated by a continuous or broad spectrum of frequencies rather than a single frequency.
Note 1: The Carson bandwidth rule is expressed by the relation CBR = 2(f + fm) where CBR is the bandwidth requirement, f is the carrier peak deviation… (Read More →)

1. call-associated signaling,
2. centralized attendant services,
3. channel-associated signaling,
4. conditional access system.

1. A series of reply posts to a message on a bulletin board system.
2. An offset stack of (usually) active windows displayed on a computer screen.
3. A connected series of essentially identical electronic circuits (for example, as might be used in serial-parallel converters).

Acronym for computer-aided software engineering, computer-aided systems engineering. Software used for the automated development of systems software, i.e., computer code.
Note 1: CASE functions include analysis, design, and programming.
Note 2: CASE tools automate methods for designing, documenting, and producing structured computer code in the desired programming language.

1. In data equipment, the change from letters to other characters, or vice versa.
2. In typewriting or typesetting, the change from lower case letters to upper case letters, or vice versa.

Technology that makes use of computer assisted software engineering (CASE) to enhance the development of systems design and development.

An antenna in which the feed radiator is mounted at or near the surface of a concave main reflector and is aimed at a convex secondary reflector slightly inside the focus of the main reflector.
Note 1: Energy from the feed unit illuminates the secondary reflector, which reflects it back to the main reflector, which then forms the desired forward… (Read More →)

Conditional Access Table

Category (cable)

The rapid reduction of the ability of a system, subsystem, component, equipment, or software to perform its intended function.
Note: Catastrophic degradation usually results in total failure to perform any function.

A component of a security clearance and/or security class used for computing access rights and controlling information flow by restricting access to the information to a specific group of subjects.
Note: [a] when more than one category is combined within a security class, access rights are granted only when all categories are present in the security clearance. [b] Adding a… (Read More →)

The ANSI/EIA/TIA-568 designation for 100-ohm unshielded twisted-pair cables and associated connecting hardware whose characteristics are specified for data transmission up to 16 Mb/s.

The ANSI/EIA/TIA-568 designation for 100-ohm unshielded twisted-pair cables and associated connecting hardware whose characteristics are specified for data transmission up to 20 Mb/s.

The ANSI/EIA/TIA-568 designation for 100-ohm unshielded twisted-pair cables and associated connecting hardware whose characteristics are specified for data transmission up to 100 Mb/s.

Abbreviation for cable TV.

Abbreviation for component analog video. A signal in which an analog voltage or current, rather than a set of numbers, represents the value of a pixel. Synonym analog component. [After Silicon]

A component of a security clearance and/or security class used for computing access rights and controlling information flow by authorizing a specific group of subjects to have access to the information.
Note: [a] When one or more caveats (of a given set) occurs within a security class, access rights are granted when: a) at least one of the caveats is… (Read More →)

A volume defined by conductor-dielectric or dielectric-dielectric reflective boundaries, or a combination of both, and having dimensions designed to produce specific interference effects (constructive or destructive) when excited by an electromagnetic wave.

Cipher Block Chaining

Categorization Based Content Screening

Constant Bit RAte

1. Connectivity Check,
2. Country Code.

Composite Capabilities/Preferences Profile

Abbreviation forcharge coupled device. A semiconductor image-sensing device that (a) is usually in the form of a plane rectangular matrix of microscopic, individual sensing elements, each of which corresponds to an image pixel, (b) is placed at the focal plane of an optical imaging system, and (c) converts the optical image into electrical signals which represent the information contained within… (Read More →)

Call Control Function

Abbreviation for connections per circuit hour.

Copy Control Information (Content Copy Information)

Abbreviation for Commission on Critical Infrastructure Protection. See Critical Infrastructure.

Abbreviation for International Radio Consultative Committee, a predecessor organization of the ITU-R.

Abbreviation for common-channel interoffice signaling.

Abbreviation for International Telegraph and Telephone Consultative Committee; a predecessor organization of the ITU-T.

Abbreviation for hundred call-seconds. See call-second.

Abbreviation for common control switching arrangement.

Abbreviation for closed-circuit TV. See closed circuit.

Call Control eXtensible Markup Language

Consumer Domain

Abbreviation for compact disk read-only memory. An optical digital storage device, of high capacity, capable of being read from but not written to.

Abbreviation 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.
Note: The extension adds ADPCM audio to permit the interleaving of sound and video data to animation and with sound synchronization. It is a component in the design of advanced multimedia computers. [After Silicon]

Abbreviation for compact disc-interactive. A compact disc format that provides audio, digital data, still graphics, and limited motion video, and that accepts variable user input to generate correspondingly variable output. [After Silicon]

Consumer Domain Device Configuration

Abbreviation for combined distribution frame.

Abbreviation for code-division multiple access.

Carbon Disclosure Project

Abbreviation for coherent differential phase-shift keying.

1. call detail recording,
2. charging data records.

Content Delivery System

1. Consumer Equipment,
2. Customer Edge,
3. Consumer Electronics

Consumer Electronic Bus

Abbreviation for comparably efficient interconnection.

1. In cellular mobile, the geographical area covered by the smaller of: a base station, or a subsystem (sector antenna) of that base station corresponding to a specific logical identification on the radio path.
Note: Mobile stations in a cell may be reached by the corresponding radio equipment of the base station.
2. The service area of an individual transmitter… (Read More →)

A quantification of variability in cell delay for an asynchronous transfer mode (ATM) layer connection. [T1.630-1999]

The identification of the asynchronous transfer mode (ATM) cell boundaries within a cell stream. [T1.646-1995]

Asynchronous transfer mode (ATM) layer protocol control information that precedes user data. [After T1.627-1993]

1. 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 these y cells that leave at the egress of the network. [T1.627-1993]
2. In a network element, the ratio (1-x/y), where y is the umber of cells that arrive… (Read More →)

A statistically multiplexed interface protocol for packet switched data communications that uses fixed-length packets, i.e., cells, to transport data.
Note 1: Cell relay transmission rates usually are between 56 kb/s and
1. 544 Mb/s, i.e., the data rate of a DS1 signal.
Note 2: Cell relay protocols (a) have neither flow control nor error correction capability, (b) are information-content independent,… (Read More →)

A mobile communications system that uses a combination of radio transmission and conventional telephone switching to permit telephone communication to and from mobile users within a specified area.
Note: In cellular mobile systems, large geographical areas are segmented into many smaller areas, i.e., cells, each of which has its own radio transmitters and receivers and a single controller interconnected with… (Read More →)

Synonym cellular mobile.

Synonym cellular mobile.

In telephony, a generic term for all wireless phones, regardless of the technology they use; the term derives from cellular base stations that receive and transmit calls. Both cellular and PCS phones use cellular technology. [After the FCC]
Note: The strategically placed rf base stations have limited, usually overlapping coverage areas (cells) that serve to connect mobile, usually small handheld… (Read More →)

Synonym cellular mobile.

Acronym for code-excited linear prediction.

1. In frequency modulation, the rest frequency, i.e., the frequency of the unmodulated carrier. Synonym carrier frequency.
2. The frequency of the middle of the bandwidth of a channel. [47CFR]
3. In facsimile systems, the frequency midway between the picture-black and picture-white frequencies.

1. A common carrier switching center in which trunks and/or loops are terminated and switched.
Note: In the DOD, "common carrier" is called "commercial carrier. " Synonym switch. Other synonyms [loosely] end office, exchange, local central office, local exchange, local office, switching exchange, telephone exchange.
2. A switching unit, in a telephone system which provides service to the general public,… (Read More →)

The 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 and X is a number from 0 to
9. Central office codes may also be referred to as “NXX codes. ” (47 C. F. R. §
5
2.… (Read More →)

Loosely, in the sense of a trunk between public and private switches, a synonym for central office trunk. See trunk.

The first three digits (N) of the seven-digit telephone number assigned to a customer's telephone exchange service when dialed on a local basis. [NECA/FCC] Synonym [loosely]prefix.

Loosely, in the sense of a trunk between public and private switches, a synonym for central office connecting facility. See trunk.

See CPU.

Synonym CPU.

A function of a usually centrally located attendant console that permits the control of multiple switches, some of which may be geographically remote.

An automatic message accounting system that serves more than one switch from a central location.
Note: When using CAMA, human intervention may be required.

Operation of a communication network in which transmission may occur between the control station and any tributary station, but not between tributary stations.

An organization provided by some communications service providers to coordinate services between the companies and vendors.

A 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. "indicates that all equipment except the attendant's position and station equipment is located in the central office. "Centrex® C. U. "indicates that all equipment, including the dial switching equipment, is located on the customer's… (Read More →)

1. In cryptography, the public key and the identity of an entity, with other information, rendered unforgeable by digitally signing the entire information with the private key of the issuing certification authority. [After X9.42] Synonym digital certificate.
2. [A] record holding security information about an information-system (IS) user and vouches to the truth and accuracy of the information it contains.… (Read More →)

In 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 bank account to prevent the fraudulent use of the account (including the transfer of funds from that account).

In cryptography, the information in a certificate which is signed. [After X9.57]

[The] process whereby certificates . . . are generated, stored, protected, transferred, loaded, used, and destroyed. [INFOSEC-99]

See CRL.

In cryptography, an integer value that is (a) unique within the issuing certificate authority (CA), and (b) unambiguously associated with a certificate issued by that CA. [After X.509]

In cryptography, a station, agency, or individual user that needs to know, with certitude, the public key of another entity. [After X.509]

1. [The] comprehensive evaluation of the technical and nontechnical security features of an IS [information system] and other safeguards, made as a part of and in support of the accreditation process, to establish the extent to which a particular design and implementation meets a set of specified security requirements. [INFOSEC-99]
2. The issue by the UK Certification Body of a… (Read More →)

[The] individual responsible for making a technical judgment of the system's compliance with stated requirements, identifying and assessing the risks associated with operating the system, coordinating the certification activities, and consolidating the final certification and accreditation packages. [INFOSEC-99]

1. In cryptography, a center trusted by one or more agencies or individuals to create and assign certificates and, optionally, to create user's keys. [After X9.31]
2. In secure communications, a trusted person or entity who issues certificates (also called "public- key certificates") for encryption purposes.
3. An independent party identifying and certifying payers and payees for real-time credit card… (Read More →)

1. An independent and impartial national organization that performs certification [ITSEC].
2. The Certification Body for the UK Evaluation and Certification Scheme is a joint CESG/DTI operation under a Scheme Management Board. Its principal role is to carry out the certification of the results of all evaluations of systems and products carried out under the auspices of the UK Scheme… (Read More →)

In cryptography, the ordered sequence of entity certificates that can be processed, with the public key of the initial entity in the path, to determine the public key of the final entity in the path. [After X9.57]

An identity in the form of an attribute in a certificate. The issuing authority will have authenticated the owner of the certificate [ECMA138].

In computer networking, one who has met proprietary training and certification requirements pertinent to network design or maintenance.
Note: The training requirements embrace both software and hardware configuration.

Person responsible for certification of a system and/or product [CESG]

A clock containing a cesium standard as a frequency-determining element.

A primary frequency standard in which electronic transitions between the two hyperfine ground states of cesium-133 atoms control the output frequency.
Note 1: The difference between the energy levels of the two hyperfine ground states of the cesium-133 atom corresponds, in the absence of external influences (e.g., the magnetic field of the Earth), to electromagnetic radiation having a frequency of… (Read More →)

Circuit Emulation Services over Ethernet

Circuit Emulation Services over Packet Switched Networks

Circuit Emulation over Packet Switched Networks

Code of Federal Regulations

Abbreviation for color graphics adapter. A low-resolution video display standard, having a pixel resolution of 320 x
20
0. [After Silicon]

1. Abbreviation for common gateway interface. A means for allowing programs or scripts (usually written in C++ or Perl) to add functionality to the World Wide Web.
Note: Examples are search engines, feedback forms, and guestbooks. [Bahorsky]
2. Abbreviation for computer graphics interface.

Abbreviation for computer graphics metafile. A digital file format (standard) used for the storage or transmission of digital representations of graphics (i.e., images).
Note: The cgm format (indicated by the filename extension ". cgm") is used most by CAD programs.

Copy Generation Management System - Analog

Synonym (in cryptosystems) bacterium.

[A] prearranged procedure in which a subject requests authentication of another, and the latter establishes validity with a correct reply. [INFOSEC-99]

The procedure of transferring signaling traffic from alternative signaling link(s) to the signaling link which has become available as a result of having been restored, uninhibited, or unblocked. This procedure performs actions opposite to changeover. [T1.226-1992]

The procedure of transferring signaling traffic from one signaling link to one or more different signaling links, when the link in use fails or is required to be cleared of traffic. [T1.110-1987]

1. A connection between initiating and terminating nodes of a circuit.
2. A single path provided by a transmission medium via either (a) physical separation, such as by multipair cable or (b) electrical separation, such as by frequency- or time-division multiplexing.
3. A path for conveying electrical or electromagnetic signals, usually distinguished from other parallel paths.
4. Used in conjunction… (Read More →)

The 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 or higher bit-rate digital channel and, conversely, demultiplexes these aggregates back into individual channels.

Binary data transmitted over a communications link.
Note: Channel bits are derived from user information by FEC (forward error correction) coding and interleaving.

1. The maximum possible information transfer rate through a channel, subject to specified constraints.
2. The rate at which information may be transmitted through a channel.
Note: Usually measured in bits per second [CESG].

A device for connecting a channel to a highway, or a highway to a channel, at specified times.

1. The ratio of the channel noise at any point in a transmission system to an arbitrary level chosen as a reference.
Note 1: The channel noise level may be expressed in (a) dB above reference noise (dBrn), (b) dB above reference noise with C-message weighting (dBrnC), or (c) adjusted dB (dBa).
Note 2: Each unit used to measure channel… (Read More →)

The constant frequency difference between a channel frequency and a reference frequency which may frequency hop.

Maximizing 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 of higher data rate.

The percentage of time a channel was available for use in a specified period of scheduled availability.
Note 1: Channel reliability is given by where To is the channel total outage time, Ts is the channel total scheduled time, and Ta is the channel total available time.
Note 2: Ts = Ta + To.

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 compatible with the network, and (d) is the last signal regeneration point, on the loop side, coming from the central office, before the regenerated signal reaches a multiplexer or data terminal equipment (DTE).

See group.

A 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.

Signaling in which the signals necessary to switch a given circuit are transmitted via the circuit itself or via a signaling channel permanently associated with it.

An application of push technology that allows users to automatically receive specific kinds of content. [Bahorsky]

The use of a single wideband, i.e., high-capacity, facility to create many relatively narrowband, i.e., lower capacity, channels by subdividing the wideband facility.

1. A letter, digit, or other symbol that is used as part of the organization, control, or representation of data.
2. One of the units of an alphabet.

A method of error detection using the preset rules for the formulation of characters.

Software that is capable of selectively removing characters from a data stream, e.g., software that removes communications-control characters so that they are not printed.

A functional unit that converts the coded representation of a character into the graphic representation of the character for display.

Preservation of a character during processing, storage, and transmission.

In a communications system, the total number of unit intervals required to transmit any given character, including synchronizing, information, error checking, or control characters, but not including signals that are not associated with individual characters.
Note: An example of a time interval that is excluded when determining character interval is any time added between the end of a stop signal… (Read More →)

The identification of characters by automatic means.

1. A finite set of different characters that is complete for a given purpose.
Note: A character set may or may not include punctuation marks or other symbols.
2. An ordered set of unique representations.
Note: Examples of character sets include the 26 letters of the English alphabet, Boolean characters 0 and 1, the 128 ASCII characters, and International Telegraph… (Read More →)

The 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 of a user-to-user connection.
Note: Character-count integrity is not the same as character integrity, which requires that the characters delivered are, in fact, exactly the same as they were originated.

Pertaining to control of start-stop teletypewriter equipment in which a device is stepped one character at a time.
Note: The step interval is equal to or greater than the character interval at the applicable signaling rate.

In telegraphy, the distortion caused by transients that, as a result of previous modulation, are present in the transmission channel.
Note: Characteristic distortion effects are not consistent. Their effects on a given signal transition are dependent upon transients remaining from previous signal transitions.

A frequency which can be easily identified and measured in a given emission. A carrier frequency may, for example, be designated as the characteristic frequency. [NTIA] [RR]

1. 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 infinitely long.
Note 1: A uniform line terminated in its characteristic impedance will have no standing waves, no reflections from the end, and a constant ratio of voltage to current at a given frequency… (Read More →)

In a recording medium, a unit of linear packing density of characters.

A unit of signaling speed used to express the number of characters passing a designated point per second.

See CCD.

In Universal Personal Telecommunications Service, the geographical location that may be used by the UPT service providers to determine the distance-related charges applying to the call originator and/or to the destination UPT user.

Abbreviation for conversational hypertext access technology. A form of interactive online typewritten communication that allows participants ("members") to engage in text-message conferencing, via real-time computer networking over designated communications facilities ("chat rooms"), without storing the messages.
Note: Participants' messages are instantaneously relayed to all other participants logged into the chat room; in turn, their replies are likewise instantaneously relayed to… (Read More →)

In computer conferencing chat, synonym forum.

An Internet relay chat (IRC) channel designated for the real-time exchange of text messages.
Note: Chat rooms are usually named in such as way as to identify the subject matter of the conversation they are intended to promote. [Bahorsky]

A batch of commands and responses, prerecorded on a terminal computer, for the purpose of facilitating easy or automatic access to a network.
Note: A chat script usually contains a user name and a password that are automatically supplied to the network machine during the login procedure.

Russian terrestrial low frequency navigation system

A process for determining accuracy.

1. A bit, such as a parity bit, derived from and appended to a bit string for later use in error detection and possibly error correction.
2. A data bit associated with a character or block for the purpose of checking the absence of error within the character or block. [T1.226-1992]

A character, derived from and appended to a data item, for later use in error detection and possibly error correction.

A digit, derived from and appended to a data item, for later use in error detection and possibly error correction.

A device that is attached to interconnect the Go and Return paths of a circuit at the incoming end of a circuit on command to permit maintenance personnel to make a continuity check on a loop basis. [T1.110-1987]

A 16-bit sequence in the last two octets of a frame (excluding flags) that offers a cyclic redundancy check (CRC). The CRC is derived over either the header in unnumbered-information-header format frames or over the entire packet frame for unnumbered-information frames (excluding flags). The algorithm used is described in ISO
330
9. [T1.312-1991]

Cipher text generated by cryptographic logic to detect failures in cryptography. [INFOSEC-99]

An element in a Web page's interactive form that allows users to select an option associated with that element.
Note: The selection is sent electronically to the Web site when the user submits the form. [After Bahorsky]

Machine instructions used in the detection or interpretation of certain data or data fields from a diskette, for the purpose of determining whether the diskette is an authorized or unauthorized copy. [2382-pt.8]

1. The sum of a group of data items, which sum is used for checking purposes.
Note 1: A checksum is stored or transmitted with the group of data items.
Note 2: The checksum is calculated by treating the data items as numeric values.
Note 3: Checksums are used in error detecting and correcting.
2. [The] value computed on data… (Read More →)

In cryptography, a computed value that results from passing a data value through an irreversible algorithm. [After X9.24]

1. Synonym integrated circuit.
2. In satellite communications systems, the smallest element of data in an encoded signal.
3. The most elemental component of a spread spectrum signal when it is decompressed in time; that is, the longest duration signal in which signal parameters are approximately constant. .
4. In micrographic and display systems, a relatively small and separate piece… (Read More →)

1. The rate of encoding. [NTIA]
2. In direct-sequence-modulation spread-spectrum systems, the rate at which the information signal bits are transmitted as a pseudorandom sequence of chips.
Note: The chip rate is usually several times the information bit rate.

In spread-spectrum systems, the duration of a chip produced by a frequency-hopping signal generator.

1. The rapid changing, as opposed to long-term drifting, of the frequency of an electromagnetic wave.
Note: Chirping is most often observed in pulsed operation of a source.
2. A pulse compression technique that uses (usually linear) frequency modulation during the pulse.

In cryptography, an analytical attack in which a cryptanalyst can submit an unlimited number of plaintext messages and examine the corresponding ciphertext. [2382-pt.8]

In television, nearly instantaneous switching between multiple video signals, based on the state, i.e., phase, of the color (chroma) signal of one, to form a single composite video signal.
Note 1: Chroma keying is used to create an overlay effect in the final picture, e.g., to insert a false background, such as a weather map or scenic view, behind the… (Read More →)

Noise that manifests itself in a video picture as colored snow. [After Silicon]

A commonly used (but redundant) synonym for material dispersion. See dispersion.

See chromaticity diagram.

A two-dimensional Cartesian plot that depicts the multidimensional subjective relationship among colors perceived by the normal human visual system (eyes and nervous system, including the brain) when additively stimulated by (two or more; usually three) discrete monochromatic visible sources (wavelengths).
Note: The familiar CIE chromaticity diagram depicts perceived colors plotted as a function of the normalized relative intensity of a… (Read More →)

The difference between a color and a specified reference color having a specified chromaticity and an equal luminance. [After Laurin]

In color television, that signal or portion of the composite signal that bears the color information.

Trunk: A trunk experiencing a much higher then normal rate of failure or switching irregularities, over a period of time, with resulting high incidence of test O. K. or no trouble found.

Carrier Identification Code

Classless Inter-Domain Routing

Abbreviation for Commission International de l'Eclairage (International Commission on Illumination). An international standards-setting organization, based in Vienna, Austria, which is concerned with the development of (a) color-matching systems, (b) recommended practices and standards concerning the properties and applications of light, and (c) methods of measurement pertaining thereto.

Common Information Model

A software file-compression scheme for video on low-power central processing units (CPUs), and typically operating with 320 x 240 pixels at 15 frames per second. [After Silicon]

1. Any cryptographic system in which arbitrary symbols, or groups of symbols, represent units of plain text or in which units of plain text are rearranged, or both. [INFOSEC-99]
2. The result of using a cipher.
Note: An example of a cipher is an enciphered message or text.

Any cryptosystem that requires the use of a key to convert, unit by unit, plain text, encoded text, or signals into an unintelligible form for secure transmission.
Note: The capability to decipher must be available at the receiving site.

1. Enciphered information. [INFOSEC-99]
Note: Cipher text is the result obtained from enciphering plain or encoded text.
2. Data produced through the use of encipherment. The semantic content of the resulting data is not available.
Note: Cipher text may itself be input to encipherment, such that super-enciphered output is produced [7498-2].

Cryptographic logic that uses previous cipher text to generate a key stream. [INFOSEC-99]

In cryptography, ciphertext that is formed by encrypting concatenated encryption elements. [After X9.23]

In cryptography, a segment of a ciphertext string. [After X9.23]

The process of enciphering audio information, resulting in encrypted speech. [INFOSEC-99]
Note: "Ciphony" is a contraction of "ciphered telephony . "

Contact Information in Presence Information Data Format

Committed Information Rate

1. The complete path between two terminals over which one-way or two-way communications may be provided.
2. An electronic path between two or more points, capable of providing a number of channels.
3. A number of conductors connected together for the purpose of carrying an electrical current.
4. An electronic closed-loop path among two or more points used for signal… (Read More →)

Information identifying a circuit between a pair of exchanges, for which signaling is being performed (14 bits in the ISDN user part). [T1.110-1987]

The route kilometers of revenue producing circuits in service, determined by measuring the length in terms of kilometers, of the actual path followed by the transmission medium. [47 CFR Pt.36-A]

At any point in a transmission system, the ratio of the circuit noise at that point to an arbitrary level chosen as a reference.
Note: The circuit noise level is usually expressed in dBrn0, signifying the reading of a circuit noise meter, or in dBa0, signifying circuit noise meter reading adjusted to represent an interfering effect under specified conditions.

The percentage of time a circuit was available for use in a specified period of scheduled availability.
Note 1: Circuit reliability is given by where To is the circuit total outage time, Ts is the circuit total scheduled time, and Ta is the circuit total available time.
Note 2: Ts = Ta + To. Synonym time availability.

The process by which a communications circuit is established between two users after disruption or loss of the original circuit.
Note: Circuit restoration is usually performed in accordance with planned procedures and priorities. Restoration may be effected automatically, e.g., by switching to a hot standby, or manually, e.g., by manual patching.

In open systems architecture, the logical path of a message in a communications network based on a series of gates at the physical network layer in the Open Systems Interconnection--Reference Model and the GOSIP FIPS PUB 146-1.

1. A method of routing traffic through a switching center, from local users or from other switching centers, whereby a connection is established between the calling and called stations until the connection is released by the called or calling station.
2. A process that, on demand, connects two or more data terminal equipments (DTEs) and permits the exclusive use of… (Read More →)

See circuit switching, switching center.

Equipment used for routing messages over common-user circuits that interconnect a source data terminal equipment (DTE) to a sink DTE for information interchange.

In ISDN applications, a transfer mode by means of permanent allocation of channels or bandwidth between connections.

A data transmission service requiring the establishment of a circuit-switched connection before data can be transferred from source data terminal equipment (DTE) to a sink DTE.
Note: A circuit-switched data transmission service uses a connection-oriented network.

In electromagnetic wave propagation, polarization such that the tip of the electric field vector describes a helix.
Note 1: The magnitude of the electric field vector is constant.
Note 2: The projection of the tip of the electric field vector upon any fixed plane intersecting, and normal to, the direction of propagation, describes a circle.
Note 3: A circularly polarized… (Read More →)

1. A passive junction of three or more ports in which the ports can be accessed in such an order that when power is fed into any port it is transferred to the next port, the first port being counted as following the last in order.
2. In radar, a device that switches the antenna alternately between the transmitter and… (Read More →)

Cybersecurity and Infrastructure Security Agency (CISA); Emergency Communications Division (ECD) – formerly OEC (see Office of Emergency Communications)

1. The application of cryptography to television signals.
2. Television signals that have been enciphered to preserve the confidentiality of the transmitted information.

1. Of an optical fiber, one or more layers of material of lower refractive index, in intimate contact with a core material of higher refractive index.
2. A process of covering one metal with another (usually achieved by pressure rolling, extruding, drawing, or swaging) until a bond is achieved.

In the cross section of a realizable optical fiber, ideally circular, but in practice assumed to a first approximation to be elliptical, the average of the diameters of the smallest circle that can be circumscribed about the cladding, and the largest circle that can be inscribed within the cladding.

See ovality.

An undesired mode that is confined to the cladding of an optical fiber by virtue of the fact that the cladding has a higher refractive index than the surrounding medium, i.e., air or primary polymer overcoat.
Note: Modern fibers have a primary polymer overcoat with a refractive index that is slightly higher, rather than lower, than that of the cladding,… (Read More →)

In an optical fiber, anything used to convert cladding modes to radiation modes, thus removing them from the fiber.
Note: In practice, the fiber's polymer overcoat (which is also used to protect it from mechanical damage and to isolate it optically from other fibers) is used as a cladding mode stripper. The refractive index of the coating material is made… (Read More →)

See ovality.

Synonym cladding noncircularity. See ovality.

See cladding mode.

Information used by a claimant to generate exchange AI needed to authenticate a principal [10181-2].

An entity which is or represents a principal for the purposes of authentication. A claimant includes the functions necessary for engaging in authentication exchanges on behalf of a principal [10181-2].

Acronym for custom local area signaling service.

Synonym (in Internet protocol) multicast address.

The set of characteristics of an emission, designated by standard symbols, e.g., type of modulation of the main carrier, modulating signal, type of information to be transmitted, and also, if appropriate, any additional signal characteristics. [NTIA] [RR]

A ranking, assigned to each switching center in a communications network, determined by the center switching functions, interrelationships with other offices, and transmission requirements.

1. A designation assigned to describe the service treatment and privileges given to a particular terminal.
2. A subgrouping of telephone users for the purpose of rate distinction.
Note: Examples of class of service subgrouping include distinguishing between (a) individual and party lines, (b) Government and non-Government lines, (c) those permitted to make unrestricted international dialed calls and those not… (Read More →)

Synonym classmark.

1. A marking applied to information, indicating the estimated damage to the national interest that would be caused by its unauthorized disclosure, and used to determine the minimum standards of protection that should be applied [CESG].
2. A component of a security clearance and/or security class used for computing access rights and controlling information flow.
Note: Access rights are granted… (Read More →)

A designator used to describe the service feature privileges, restrictions, and circuit characteristics for lines or trunks that access a switch.
Note: Examples of classmarks include precedence level, conference privilege, security level, and zone restriction. Synonym class-of-service mark.

To cause one or more storage locations to be in a prescribed state, usually that corresponding to a zero or that corresponding to the yyspace character.

1. In radio broadcasting, a frequency assigned for the exclusive use of one entity.
2. In networking, a signal path that provides its full bandwidth for a user's service.
Note: No control or signaling is performed on this path.

A characteristic of a transmission path in which the bit position allocated for customer data may represent any combination of zeros and ones. For the DS1 rate, the bits allocated for customer data are the last 192 bits of each frame. [T1.408-1990]

Contention that occurs when a DTE and a DCE simultaneously transfer a clear request packet and a clear indication packet specifying the same logical channel.
Note: The DCE will consider that the clearing is completed and will not transfer a DCE clear confirmation packet.

A call control signal used to acknowledge reception of the data-terminal-equipment (DTE) clear request by the data circuit-terminating equipment (DCE) or to acknowledge the reception of the DCE clear indication by the DTE.

1. A message that (a) is sent in the forward direction and the backward direction, (b) contains a circuit-released signal or circuit-released acknowledgment signal, and (c) usually contains an indication of whether the message is in the forward or the backward direction.
2. A message in plain language, i.e., not enciphered.

1. Intelligible data, the semantic content of which is available.
2. Synonym plain text.

1. Intelligible data, the semantic content of which is available [7498-2].
2. See: Security Clearance [CESG].

1. A sequence of events used to disconnect a call and return to the ready state.
2. Removal of data from an information system (IS), its storage devices, and other peripheral devices with storage capacity, in such a way that the data may not be reconstructed using common system capabilities (i.e., keyboard strokes); however, the data may be reconstructed using… (Read More →)

1. In an optical fiber, a deliberate, controlled break, intended to create a perfectly flat endface, perpendicular to the longitudinal axis of the fiber.
Note: A cleave is made by first introducing a microscopic fracture ("nick") into the fiber with a special tool, called a "cleaving tool,"which has a sharp blade of hard material, such as diamond, sapphire, or tungsten… (Read More →)

Abbreviation for competitive local exchange carrier. The new local exchange carrier that is attempting to compete outside its traditional operating territory. [After FCC]

See Equipment Code (CLEI™ Code) A Common Language Equipment Identifier (CLEI™) Code is a structured 10-character alpha-numeric code, providing a standard method of identifying communication assets.

(CLEI™ is a trademark of Telcordia Technologies, Inc. .. dba iconectiv, llc. )

Data obtained by analyzing the log file containing information regarding who has accessed the Web page or the banner under consideration.

Of a Web page menu item, especially an advertisement, the ratio of (a) the number of time it is selected ("clicked") to (b) the number of times it is viewed.

The process of clicking on a Web advertisement and going directly to the advertiser's Web site. Synonyms ad clicks, clicks, requests.

Synonym click-through.

1. In networking, a software application that allows the user to access a service from a server computer, e.g., a server computer on the Internet or a LAN.
2. A computer, e.g., a desktop computer on a LAN, that is so served.

A unique identification number used when sending data to a specific client. Clients that are standardized for use in generic applications are allocated standard client IDs (listed in this standard). Client IDs also may be assigned for non-standard or proprietary applications using the manufacturer-specific mechanism described. [T1.80
0. 08-1995]

Any hardware/software combination that generally adheres to a client-server architecture, regardless of the type of application.

Any network-based software system that uses client software to request a specific service, and corresponding server software to provide the service from another computer on the network.

In the digital transmission of analog signals, including analog television and digital audio broadcasting (DAB), a signal-quality effect in which the decoded analog signal is either essentially flawless or totally unusable; i.e., it exhibits no gradual degradation or improvement attributable to the presence or absence of transient phenomena such as amplitude variations that may occur during transmission.
Note: The cliff… (Read More →)

1. In moving picture or television technology, a relatively short, continuous set of frames (often including the associated audio, if any), stored on a recording medium. Synonyms take, scene.
2. In audio, a short, uninterrupted sound track.
Note: Both audio and video clips may be part of a digitized information package, e.g., on a Web page.
3. To limit to… (Read More →)

1. A circuit or device that limits the instantaneous output signal amplitude to a predetermined maximum value, regardless of the amplitude of the input signal.
2. A chip developed by the United States Government that was to be used as the standard chip in all encrypted communications. Aside from the fact that all details of how the Clipper chip work… (Read More →)

1. In telephony, the loss of the initial or final parts of a word, words, or syllable, usually caused by the nonideal operation of voice-actuated devices.
2. The limiting of instantaneous signal amplitudes to a predetermined maximum value.
3. In a display device, the removal of those parts of display elements that lie outside of a given boundary.

See Location Code (CLLI™ Code). A Common Language Location Identifier (CLLI™) Code is a a standardized eleven-character code that identifies the geographic location and identifies switches, points of interconnection, and other functional categories of telephony network elements.

(CLLI™ is a registered trademark of iconectiv, llc. iconectiv is a registered trademark of iconectiv, llc. )

1. A reference source of timing information.
2. A device providing signals used in a transmission system to control the timing of certain functions such as the duration of signal elements or the sampling rate.
3. A device that generates periodic, accurately spaced signals used for such purposes as timing, regulation of the operations of a processor, or generation of… (Read More →)

The level of agreement of the frequency of a clock with the ideal frequency. This is specified as the magnitude of the fractional frequency offset from the ideal frequency. [T1.10
5. 09-1996]

The difference between local clock time or value and a designated reference clock time or value.
Note: Subtracting the clock difference from the local clock brings the local clock into agreement with the reference clock.

An operating condition of a clock in which it is locked to an external reference and is using time constants that are altered to quickly bring the local oscillator's frequency into approximate agreement with the synchronization reference frequency. [T1.101-1987]

An operating condition of a clock in which its local oscillator is not locked to an external synchronization reference, and is using no storage techniques to sustain its accuracy. [T1.101-1987]

An operating condition of a clock that has lost its controlling input and is using stored data, acquired while in normal operation, to control its output. The stored data is averaged to minimize the effects of short-term variations, allowing the normal conditions to be simulated within specifications. Holdover terminates when the output of the clock is no longer controlled by… (Read More →)

An operating condition of a clock in which the output signals are controlled by an external input reference. It is the expected mode. In normal mode, each clock in a chain has the same long-term average frequency, and the time error between the input and output of each clock is bounded. Only stratum 1 sources of timing require no input… (Read More →)

The rate of relative phase change between a given clock signal and a stable reference signal.
Note: The two signals are generally at or near the same frequency or have an integral multiple frequency relationship.

The rate at which a clock issues timing pulses.
Note: Clock rates are usually expressed in pulses per second, such as
4. 96 Mp/s (megapulses per second).

The maximum permissible departure of a clock indication from a designated time reference such as Coordinated Universal Time (UTC).

A track on which a pattern of signals is recorded to provide a timing reference.

Synonym right-hand (or clockwise) polarized wave.

In broadcast and cable television, the insertion, into the blank lines between frames, of information that may be decoded and displayed on the screen as written words corresponding to those being spoken and transmitted via the conventional audio subcarrier.
Note: Closed captioning, developed for the hearing-impaired, requires a special decoder, which may be external to, or built into, the television… (Read More →)

1. In radio and television transmission, pertaining to an arrangement in which programs are directly transmitted to specific users and not broadcast to the general public.
2. In telecommunications, a circuit dedicated to specific users.
3. A completed electrical circuit.

In a network, a group of users permitted to communicate with each other but not with users outside the group.
Note: A user data terminal equipment (DTE) may belong to more than one closed user group.

A closed user group in which at least one member of the group has a facility that permits communication with one or more users external to the closed user group.

An electromagnetic waveguide (a) that is tubular, usually with a circular or rectangular cross section, (b) that has electrically conducting walls, (c) that may be hollow or filled with a dielectric material, (d) that can support a large number of discrete propagating modes, though only a few may be practical, (e) in which each discrete mode defines the propagation constant… (Read More →)

The integral, over all frequencies, of the absolute value of the closed-loop transfer function of a phase-locked loop.
Note: The closed-loop noise bandwidth, when multiplied by the noise spectral density, gives the output noise power in a phase-locked loop.

In cryptography, the originator's confirmation of the integrity of the entire transaction, i.e., of both the transaction request and its transaction response. [After X9.19]

A mathematical expression (algorithm) describing the net result of the effects of a closed (feedback) loop on the input signal to the circuits enclosed by the loop.
Note 1: The closed-loop transfer function is measured at the output.
Note 2: The output signal waveform can be calculated from the closed-loop transfer function and the input signal waveform.

1. 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. [2382-pt.8]
2. [An] environment providing sufficient assurance that applications and equipment are protected against the introduction of malicious logic during an information system (IS) life cycle. Closed security is based… (Read More →)

Synonym splice closure.

In the transmission of electromagnetic signals, attenuation caused by absorption and scattering by water or ice particles in clouds.
Note: The amount of cloud attenuation depends on many factors, including (a) the density, particle size, and turbulence of the clouds and (b) the transmission path length in the clouds.

Configuration Management

Common Management Information Protocol

Centralized Management Protocol

Abbreviation for common-mode rejection ratio.

Commercial Mobile Radio Service

Core Network

Abbreviation for carrier-to-noise ratio, combat-net radio.

Abbreviation forcomplementary network service.

Central Office

A point in time at which the quantity of TNs within existing CO codes (NXX) which are “Available for Assignment” equals zero within a switching entity/Point Of Interconnection (POI) or, conversely, when the quantities of “TNs Unavailable for Assignment” equal 10,000 times the quantity of existing CO codes (NXX) assigned to a switching entity/POI. Where CO code sharing occurs or… (Read More →)

Entity(ies) responsible for the administration of the NXXs within an NPA.

Interference caused by another signal operating on the same channel.

Acronym for customer owned and maintained equipment. Deprecated term. See customer premises equipment.

An Earth station in the fixed-satellite service or, in some cases, in the maritime mobile-satellite service, located at a specified fixed point on land to provide a feeder link for the maritime mobile-satellite service. [NTIA] [RR]

A land station in the maritime mobile service. [RR]

In timing-dependent systems, a free-running operational timing mode in which continuous or periodic measurement of clock error, i.e., of timing error, is not made.
Note: Operation in the coasting mode may be enhanced for a period of time by using clock-error data or clock-correction data (obtained during a prior period of operation in the tracking mode) to estimate clock corrections.

See primary coating.

See coaxial cable.

1. A cable consisting of a center conductor surrounded by an insulating material and a concentric outer conductor and optional protective covering, all of circular cross-section. Synonym (when combined with others under a common sheath) coaxial tube.
2. A cable consisting of multiple coaxial tubes under a single protective sheath.
Note: Coaxial cables are used primarily for CATV and other… (Read More →)

See patch bay.

Acronym for common business oriented language. A programming language designed for business data processing.

Content on Demand

1. A set of unambiguous rules specifying the manner in which data may be represented in a discrete form.
Note 1: Codes may be used for brevity or security.
Note 2: Use of a code provides a means of converting information into a form suitable for communications, processing, or encryption.
2. [In COMSEC, any] system of communication in which arbitrary… (Read More →)

Document containing plain text and code equivalents in a systematic arrangement, or a technique of machine encryption using a word substitution technique. [INFOSEC-99]

A character that (a) is used to represent a discrete value or symbol and (b) is derived in accordance with a code.

1. Conversion of signals, or groups of signals, in one code into corresponding signals, or groups of signals, in another code.
2. A process for converting a code of some predetermined bit structure, such as 5, 7, or 14 bits per character interval, to another code with the same or a different number of bits per character interval.
Note: In… (Read More →)

One of a set of parts of which the characters in a given code may be composed.

[A] group of letters, numbers, or both in a code system used to represent a plain text word, phrase, or sentence. [INFOSEC-99]
Note: Code groups may include symbols and other elements.

An assignee of an NXX code which was allocated by the CO Code Administrator. When an NXX Code becomes pooled, the Code Holder becomes the LERG Assignee

A service feature by which certain terminals are prevented from accessing certain features of the network.

The complete set of representations defined by a particular code and language.

The basic characteristics of a code: its length and generic representation.

[A] set of plain text words, numerals, phrases, or sentences for which code equivalents are assigned in a code system. [INFOSEC-99]

1. In a code, a word that consists of a sequence of symbols assembled in accordance with the specific rules of the code and assigned a unique meaning.
Note: Examples of code words are error-detecting-or-correcting code words and communication code words, such as SOS, MAYDAY, ROGER, TEN-FOUR, and OUT.
2. A cryptonym used to identify sensitive intelligence data. [JP 1-02]… (Read More →)

A coding scheme, used as a modulation technique, in which multiple channels are independently coded for transmission over a single wideband channel.
Note 1: In some communication systems, CDMA is used as an access method that permits carriers from different stations to use the same transmission equipment by using a wider bandwidth than the individual carriers. On reception, each carrier… (Read More →)

An analog-to-digital voice coding scheme.

Synonym code-transparent data communication.

A mode of data communication that uses protocols that do not depend for their correct functioning on the data character set or data code used. Synonymcode-independent data communication.

1. Acronym for coder-decoder.
1. An assembly consisting of an encoder and a decoder in one piece of equipment.
2. A circuit that converts analog signals to digital code and vice versa.
3. An electronic device that converts analog signals, such as video and voice signals, into digital form and compresses them to conserve bandwidth on a transmission path.
Note:… (Read More →)

A character set established in accordance with unambiguous rules that define the character set and the one-to-one relationships between the characters of the set and their coded representations.

A representation of a display image in a form suitable for storage and processing.

A set of elements onto which another set of elements has been mapped according to a code.
Note: Examples of coded sets include the list of names of airports that is mapped onto a set of corresponding three-letter representations of airport names, the list of classes of emission that is mapped onto a set of corresponding standard symbols, and the… (Read More →)

1. In communications systems, the altering of the characteristics of a signal to make the signal more suitable for an intended application, such as optimizing the signal for transmission, improving transmission quality and fidelity, modifying the signal spectrum, increasing the information content, providing error detection and/or correction, and providing data security.
Note: A single coding scheme usually does not provide… (Read More →)

Synonym code.

In military communications systems, a message in which the entire address is encrypted with the message text.

Abbreviation for centralized ordering group.

Pertaining to an electromagnetic wave, the area of a surface perpendicular to the direction of propagation, over which the electromagnetic wave maintains a specified degree of coherence.
Note: The specified degree of coherence is usually taken to be
0. 88 or greater.

See degree of coherence.

The propagation distance from a coherent source to a point where an electromagnetic wave maintains a specified degree of coherence.
Note 1: In long-distance transmission systems, the coherence length may be reduced by propagation factors such as dispersion, scattering, and diffraction.
Note 2: In optical communications, the coherence length, L, is given approximately by L = 2/(n), where is the… (Read More →)

For an electromagnetic wave, the time over which a propagating wave may be considered coherent.
Note 1: In long-distance transmission systems, the coherence time may be reduced by propagation factors such as dispersion, scattering, and diffraction.
Note 2: In optical communications, coherence time, , is calculated by dividing the coherence length by the phase velocity of light in a medium;… (Read More →)

Pertaining to a fixed phase relationship between corresponding points on an electromagnetic wave.
Note: A truly coherent wave would be perfectly coherent at all points in space. In practice, however, the region of high coherence may extend over only a finite distance.

Synonym aligned bundle.

Phase-shift keying (a) that is used for digital transmission, (b) in which the phase of the carrier is discretely modulated in relation to the phase of a reference signal and in accordance with data to be transmitted, and (c) in which the modulated carrier is of constant amplitude and frequency.
Note: A phase comparison is made of successive pulses, and… (Read More →)

In pulsed carrier transmission, a method of operation in which a fixed phase relationship of the carrier wave is maintained from one pulse to the next.

See coherent.

Pertaining to spare electronic equipment that is available for substitute use, but is not powered or warmed up and ready for use.

[In security, a] procedure for initially keying crypto-equipment. [INFOSEC-99]

Synonym group address.

Routing in which a switching center automatically delivers messages to a specified list of destinations.
Note 1: Collective routing avoids the need to list each single address in the message heading.
Note 2: Major relay stations usually transmit messages bearing collective-routing indicators to tributary, minor, and other major relay stations.

The process by which a divergent or convergent beam of electromagnetic radiation is converted into a beam with the minimum divergence or convergence possible for that system (ideally, a bundle of parallel rays).

A device that renders divergent or convergent rays more nearly parallel.
Note: The degree of collimation (parallelism) should be stated.

An array of dipole antennas mounted in such a manner that every element of each antenna is in an extension, with respect to its long axis, of its counterparts in the other antennas in the array.
Note: A collinear array is usually mounted vertically, in order to increase overall gain and directivity in the horizontal direction. When stacking dipole antennas… (Read More →)

1. In a data transmission system, the situation that occurs when two or more demands are made simultaneously on equipment that can handle only one at any given instant.
2. In a computer, the situation that occurs when an attempt is made to store simultaneously two different data items at a given address that can hold only one of the… (Read More →)

In color television technology, a calibration process involving adjustment of the relative amplitudes of the signal levels representing the tristimulus colors to (a) achieve a camera output signal or (b) monitor display such that the resulting additive mixture of the excited phosphors accurately creates the perception of white.

The color bar test signal shown in the associated figure, consists of discrete steps of chroma and luminance levels that produce eight different colors superimposed upon standard synchronizing and blanking signals. [T
1. Rpt16-1992]

1. In color television technology, any of several electronically generated video test patterns displayed as vertical bars of usually equal width, and of specified color (e.g., 6 hues, plus gray and black) and intensity, used to establish or verify a proper color reference; e.g., prior to broadcasting or recording.
2. Loosely, the signal that produces color bars.

In analog color television technology, a signal consisting of several (8 to 10 in NTSC) cycles of unmodulated color subcarrier, superimposed at a specified location within the composite signal.
Note: The color burst (a) enables the color-decoding circuits in the receiver, and (b) serves as an amplitude, frequency, and phase reference to which the local color (subcarrier frequency) oscillator in… (Read More →)

Computation of the tristimulus values of colors in terms of one set of primaries.
Note: This computation may be performed electrically in a color television system. [IEEE] [After SMPTE]

In television and computer graphics, the electronic adjustment of a color reproduction process to improve the perceived-color conformity of the reproduction to the original. [After IEEE 100] [After SMPTE]

In color television technology, of a receiver, the circuitry that separates the chroma information from the video (gray-scale) information and processes the former into its constituent signal components.

In video systems, distortion of hues in all or a portion of the received image.

Synonym chroma keying.

In color television technology, the instantaneous phase of the chroma signal with respect to that of the color burst signal.
Note: The phase of the chroma signal at any given instant determines the color balance of the video signal at that instant.

In color television technology, electronic alteration of the color information content to effect a change in the color balance of the video signal.

In analog color television technology, a signal superimposed upon the picture (gray scale) information for the purpose of conveying the associated color information.
Note: The color information is conveyed by the instantaneous phase of the color subcarrier with respect to that of the color burst.

Of an electromagnetic source, especially in the optical regime, the hue or wavelength (spectral content) expressed or specified as the hypothetical wavelength(s) emitted by an ideal blackbody having an absolute temperature of n kelvins (n K).
Note 1: Higher numbers indicate hues in or toward the blue; lower numbers indicate hues in or toward the red.
Note 2: Examples of… (Read More →)

The chrominance vectors carrying the color information in a composite format.
Note: The color-difference signals have been defined by the ITU-R for existing television systems.

1. The tristimulus values corresponding to monochromatic stimuli of equal radiant power.
Note: The three values of a set of color-matching functions at a given wavelength are called the color-matching coefficients. The color-matching functions may be used to calculate the tristimulus values of a color stimulus from the color stimulus function. [After SMPTE]
2. The tristimulus value per unit wavelength… (Read More →)

1. Measurement of colors based on a set of conventions. [After SMPTE]
2. The science of, or body of techniques employed in, (a) the measurement or characterization of color, and (b) the interpretation of the results.
Note: Human perception of color is a subjective phenomenon resulting from and dependent upon the properties of the eye and the brain.

A radio operating in a network that (a) provides a half-duplex circuit and (b) uses either a single radio frequency or a discrete set of radio frequencies when in a frequency hopping mode.
Note: CNRs are primarily used for push-to-talk-operated radio nets for command and control of combat, combat support, and combat service support operations among ground, sea, and air… (Read More →)

A device having at least one output channel and one or more input channels, all characterized by discrete states, such that at any instant the state of each output channel is completely determined by the states of the input channels at the same instant.

The common use of communications facilities by two or more military services, each belonging to a different nation.
Note: Such use might be specified by a combined communications-electronics agency.

A distribution frame that combines the functions of main and intermediate distribution frames and contains both vertical and horizontal terminating blocks.
Note 1: The vertical blocks are used to terminate the permanent outside lines entering the station. Horizontal blocks are used to terminate inside plant equipment. This arrangement permits the association of any outside line with any desired terminal equipment.… (Read More →)

A load-sharing collection of more than one link set to the same message destination. [T1.226-1992]

In high-level data-link control (HDLC) operation, the station that is usually responsible for performing balanced link-level operations and that generates commands, interprets responses, interprets received commands, and generates responses.

See maximal-ratio combiner.

Acronym for communications intelligence.

Synonym communications center.

A code constructed so that any partial code word, beginning at the start of a code word but terminating prior to the end of that code word, is not a valid code word.
Note 1: The comma-free property permits the proper framing of transmitted code words when (a) external synchronization is provided to identify the start of the first code… (Read More →)

1. An order for an action to take place.
2. In data transmission, an instruction sent by the primary station instructing a secondary station to perform some specific function.
3. In signaling systems, a control signal.
4. In computer programming, that part of a computer instruction word that specifies the operation to be performed.
5. Loosely, a mathematical or logic… (Read More →)

The exercise of authority and direction by a properly designated commander over assigned forces in the accomplishment of the mission. Command and control functions are performed through an arrangement of personnel, equipment, communications, facilities, and procedures employed by a commander in planning, coordinating, and controlling forces and operations in the accomplishment of the mission. [JP1-02]

The facilities, equipment, communications, procedures, and personnel essential to a commander for planning, directing, and controlling operations of assigned forces pursuant to the missions assigned. [JP 1-02]

The integrated use of operations security (OPSEC), military deception, psychological operations (PSYOP), electronic warfare (EW), and physical destruction, mutually supported by intelligence, to deny information to, influence, degrade, or destroy adversary command and control capabilities, while protecting friendly command and control capabilities against such actions.
Note: Command and control warfare applies across the operational continuum and all levels of conflict.… (Read More →)

In data transmission, a frame, containing a command, transmitted by a primary station.

1. The form or point of interface, usually indicated by a command prompt, on some operating systems in which a command is entered. [Bahorsky]
2. Describing a system that uses a command-line interface. [Bahorsky]

A list of all the different commands that may be given to a computer or communications system by an operator.
Note: Commands on a command menu may be selected by the operator by (a) using an electromechanical pointer, such as a light pen, (b) touching the display screen with a finger, (c) speaking to a voice-recognition system, or (d) positioning… (Read More →)

A communications network which connects an echelon of command with some or all of its subordinate echelons for the purpose of command and control. [JP 1-02]

A protocol data unit (PDU) transmitted by a logical link control (LLC) sublayer in which the PDU command/response (C/R) bit is equal to "0".

The capabilities required by commanders to exercise command and control of their forces. [JCS Pub 18, Operations Security, Dec.198
2. ]

1. Integrated systems of doctrine, procedures, organizational structures, personnel, equipment, facilities, and communications designed to support a commander's exercise of command and control, through all phases of the operational continuum. [JP1]
2. Integrated systems of doctrine, procedures, organizational structures, personnel, equipment, facilities, and communications designed to support a commander's exercise of command and control, across the range of military operations.… (Read More →)

The facilities, computer equipment, communications equipment, display devices, and intelligence systems necessary to support military operations.

Synonym common carrier.

Evaluations conducted under UK Information Technology Evaluation and Certification Scheme may only take place in approved evaluation facilities. Commercial companies wishing to offer evaluation services may be licensed by the Certification Body of the Scheme as Commercial Licensed Evaluation Facilities [CESG].

In military communications systems, the processing of a message from (a) a given military network, such as a tape-relay network, a point-to-point telegraph network, a radio-telegraph network, or the DSN to (b) a commercial communications network.
Note: Commercial refiling of a message will usually require a reformatting of the message, particularly the heading.

The application, i.e., insertion, of information into any data repository of an integrated database management system in a distributed local communications network.

A single electrical power source used to energize more than one circuit, component, equipment, or system.
Note 1: A common battery is usually an electrolytic device and is usually centrally located to the equipment that it serves.
Note 2: In many telecommunications applications, the common battery is at a nominal -48 Vdc.
Note 3: A central office common battery supplies… (Read More →)

The set of metallic components that are intentionally or incidentally interconnected to provide the principal means for effecting bonding and grounding inside a telecommunications building. These components include: structural steel or reinforcing rods, metallic plumbing, ac power conduit, cable racks, and bonding conductors. The CBN is connected to the exterior grounding electrode system. Synonym integrated ground plane. [After T1.320-1994]

In a telecommunications context, a telecommunications company that holds itself out to the public for hire to provide communications transmission services.
Note: In the United States, such companies are usually subject to regulation by Federal and state regulatory commissions. Synonyms carrier, commercial carrier, communications common carrier, [and, loosely] interexchange carrier.

Channels between switching offices used to transmit signaling information independent of the subscribers' communication paths or transmission channels. [47 CFR Pt.36-A]

A network consisting of two or more signaling points and connecting common channel signaling links that are administered in common. [T1.110-1987]

An automatic switching arrangement in which the control equipment necessary for the establishment of connections is shared by being associated with a given call only during the period required to accomplish the control function for the given call.
Note: In common control, the channels that are used for signaling, whether frequency bands or time slots, are not used for message… (Read More →)

An arrangement in which switching for a private network is provided by one or more common control switching systems.
Note: The switching systems may be shared by several private networks and also may be shared with the public telephone networks.

An automatic switching system that makes use of common equipment to establish a connection.
Note: The common equipment then becomes available to establish other connections.

Equipment used by more than one system, subsystem, component, or other equipment, such as a channel or switch.

[In security,] one of a family of devices developed to read-in, transfer, or store key. [INFOSEC-99]

See CGI.

A protocol used by an application process to exchange information and commands for the purpose of managing remote computer and communications resources.

A service that specifies the service interface to the Common Management Information Protocol (CMIP).
Note: To transfer management information between open systems using CMIS/CMIP, peer connections, i.e., associations, must be established. This requires the establishment of an Application Layer association, a Session Layer connection, a Transport Layer connection, and, depending on supporting communications technology, Network Layer and Link Layer connections.

A return path that is common to two or more circuits and that serves to return currents to their source or to ground.

In a line or circuit, the dc potential difference between ground and the common return.

A trunk group between exchange carrier switches which transports access traffic for numerous interexchange carriers concurrently and may also carry exchange carrier (EC) traffic. [T
1. Rpt 11-1991]

In communications systems, pertaining to communications facilities and services provided to essentially all users in the area served by the system, rather than to one user or to a relatively small number of users, such as a closed user group with outgoing access.

A circuit designated to furnish a communication service to a number of users.

A system of circuits or channels allocated to furnish communication paths between switching centers to provide communication service on a common basis to all connected stations or subscribers. It is sometimes described as a general purpose network. [JP1]

Signaling in which the signaling power of a telephone is supplied by the serving switch.
Note: In common-battery signaling, "talking power" may be supplied by common or local battery.

In multichannel switched networks, a method of transmitting all signaling information for a group of trunks by encoding it and transmitting it over a separate channel using time-division digital techniques.

1. In a multichannel communications system, signaling in which one channel in each link is used for signaling to control, account for, and manage traffic on all channels of the link.
Note: The channel used for common-channel signaling does not carry user information.
2. A signaling method in which a single channel conveys, by means of labeled messages, signaling information… (Read More →)

1. Interference that appears between signal leads, or the terminals of a measuring circuit, and ground.
2. A form of coherent interference that affects two or more elements of a network in a similar manner (i.e., highly coupled) as distinct from locally generated noise or interference that is statistically independent between pairs of network elements.

The ratio of the common-mode interference voltage at the input of a circuit, to the corresponding interference voltage at the output.

1. The voltage common to both input terminals of a device.
2. In a differential amplifier, the unwanted part of the voltage between each input connection point and ground that is added to the voltage of each original signal. Synonym longitudinal voltage.

1. A quality that applies to materiel or systems: (a) possessing like and interchangeable characteristics enabling each to be utilized, or operated and maintained by personnel trained on the others without additional specialized training; (b) having interchangeable repair parts and/or components; (c) applying to consumable items interchangeably equivalent without adjustment.
2. Pertaining to equipment or systems that have the quality… (Read More →)

An attribute describing the special arrangement for transferring information between two or more access points; it completes the structure associated with a telecommunication service as it associates the relationship between the access points involved and the flow of information between these access points. Values associated with this attribute are point-to-point, multipoint, and broadcast. [T1.603-1990] [T1.604-1990]

A function in an open system that provides the means for cooperating processes in different real open systems to communicate. This communication is concerned not only with the transfer of information between open systems, but also with their capability to interwork to accomplish a specific operations, administration, maintenance and provisioning (OAM & P) function. [T1.210-1993]

That part of the API devoted to communications with other application software, external data transport facilities, and devices. The services provided are those whose protocol state, syntax, and format all must be standardized for interoperability [POSIX.0].

1. Information transfer, among users or processes, according to agreed conventions.
2. The branch of technology concerned with the representation, transfer, interpretation, and processing of data among persons, places, and machines.
Note: The meaning assigned to the data must be preserved during these operations.

Synonymbase communications.

1. A cessation of communications or communications capability caused by a lack of power to a communications facility or equipment.
2. A total lack of communications capability caused by propagation anomalies, e.g., those present during strong auroral activity or during the re-entry of a spacecraft into the Earth's atmosphere.

1. An agency charged with the responsibility for handling and controlling communications traffic. The center normally includes message center, transmitting, and receiving facilities. [JP 1-02]
2. A facility that (a) serves as a node for a communications network, (b) is equipped for technical control and maintenance of the circuits originating, transiting, or terminating at the node, (c) may contain message-center… (Read More →)

See channel.

1. The term "communications common carrier" as used in this part [of 47CFR] means any person (individual, partnership, association, joint-stock company, trust, corporation, or other entity) engaged as a common carrier for hire, in interstate or foreign communication by wire or radio or in interstate or foreign radio transmission of energy, including such carriers as are described in subsection 2(b)… (Read More →)

Concealing or altering of characteristic communications patterns to hide information that could be of value to an adversary. [INFOSEC-99]

1. Deliberate transmission, retransmission, or alteration of communications to mislead an adversary's interpretation of the communications. [NIS]
2. Use of devices, operations, and techniques with the intent of confusing or misleading the user of a communications link or a navigation system. [JP 10-2]

Technical and intelligence information derived from foreign communications by other than the intended recipients. [JP 1-02]

1. The portion of electronic jamming that is directed against communications circuits and systems.
2. The prevention of successful radio communications by the use of electromagnetic signals, i.e., the deliberate radiation, reradiation, or reflection of electromagnetic energy with the objective of impairing the effective use of electronic communications systems.
Note: The aim of communications jamming is to prevent communications by… (Read More →)

An organization of stations capable of direct communication on a common channel or frequency. [JP 1-02] Synonym net.

See net operation.

An organization of stations capable of intercommunications, but not necessarily on the same channel. [JP 1-02]

A computer embedded in a communications system.
Note 1: An example of a CPU is the message data processor of a DDN switching center.
Note 2: CPU is also an abbreviation for central processing unit of a computer.

[An] analytic model of communications associated with an organization or activity. The model is prepared from a systematic examination of communications content and patterns, the functions they reflect, and the communications security measures applied. [INFOSEC-99]

The application of communications security (COMSEC) measures to telecommunications systems in order (a) to deny unauthorized persons access to sensitive unclassified information of value, (b) to prevent disruption of telecommunications services, or (c) to ensure the authenticity of information handled by telecommunications systems.

See protocol.

The probability that information transmitted from a communications station will arrive at the intended destination in a timely manner without loss of content.

An orbiting vehicle that relays signals between (a) terrestrial communications stations, (b) a terrestrial communications station and another communications satellite, or (c) other communications satellites.

See saturation.

1. Measures and controls taken to deny unauthorized persons information derived from telecommunications and to ensure the authenticity of such telecommunications.
Note: Communications security includes cryptosecurity, transmission security, emission security, and physical security of COMSEC material. [INFOSEC]
·(a) cryptosecurity: [The] component of communications security that results from the provision of technically sound cryptosystems and their proper use. [NIS]
·(b) emission… (Read More →)

See COMSEC equipment.

See COMSEC material.

The avoidance of any type of transmission, emission, or radiation by any means, including radiation from receiving equipment.
Note: An example of communications silence is the maintaining of a listening watch only if the receivers do not radiate beyond a specified level.

See sink.

See source.

A functional unit or operational assembly that is smaller than the larger assembly under consideration.
Note: Examples of communications subsystems in the Defense Communications System (DCS) are (a) a satellite link with one Earth terminal in CONUS and one in Europe, (b) the interconnect facilities at each Earth terminal of the satellite link, and (c) an optical fiber cable with… (Read More →)

The ability of communications systems to continue to operate effectively under adverse conditions, though portions of the system may be damaged or destroyed.
Note: Various methods may be used to maintain communications services, such as using alternate routing, different transmission media or methods, redundant equipment, and sites and equipment that are radiation hardened.

A collection of individual communications networks, transmission systems, relay stations, tributary stations, and data terminal equipment (DTE) usually capable of interconnection and interoperation to form an integrated whole.
Note: The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, and operate in unison.

The translation of user requirements for the exchange of information into cost-effective and low-risk technical solutions in terms of equipment and subsystems.
Note: Communications system engineering encompasses the integration of these parts into a complete entity resulting in a minimum investment for the entire system life cycle required to satisfy the requirements of a majority of users of the communication… (Read More →)

See survivability.

Theory that is devoted to the probabilistic characteristics of the transmission of data in the presence of noise, and that is used to advance the design, development, and operation of communications systems.

The monitoring of one or more communications lines, frequencies, or channels to obtain information by listening to or receiving all transmissions on them and transmitting and receiving messages as required.

The rear part of the theater of war or theater of operations that contains the lines of communications, theater logistics bases, forward operating bases, and other agencies required for the immediate support and maintenance of the field forces. It extends back to the CONUS base. [JP 1-02]

The specialized field concerned with the use of electronic devices and systems for the acquisition or acceptance, processing, storage, display, analysis, protection, disposition, and transfer of information.
Note: C-E includes the wide range of responsibilities and actions relating to (a) electronic devices and systems used in the transfer of ideas and perceptions, (b) electronic sensors and sensory systems used in… (Read More →)

See cable TV.

A grouping of users who generate a majority of their traffic in calls to other members of the group.
Note: The community of interest may be related to a geographic area or to an administrative organization. Synonym special interest group.

The reception of emissions from a space station in the broadcasting-satellite service by receiving equipment, which in some cases may be complex and have antennae larger than those used for individual reception, and intended for use:
by a group of the general public at one location;
or
through a distribution system covering a limited area. [NTIA] [RR]

The definition of the basic security principles and policy for a community of interconnected systems thereby allowing a series of bilateral SISPs to be produced while preserving the security of the whole. [CESG]. See also: System Interconnection Security policy.

Coordinated Multi-Point

See data compaction.

See CD ROM.

See data compaction.

An operation in which the dynamic range of signals is compressed before transmission and is expanded to the original value at the receiver.
Note: The use of companding allows signals with a large dynamic range to be transmitted over facilities that have a smaller dynamic range capability. Companding reduces the noise and crosstalk levels at the receiver.

A device that incorporates a compressor and an expander, each of which may be used independently.

A unique four-character alphanumeric code that identifies service providers.

An equal-access concept developed by the FCC stating that, ". . . if a carrier offers an enhanced service, it should be required to offer network interconnection (or collocation) opportunities to others that are comparably efficient to the interconnection that its enhanced service enjoys. Accordingly, a carrier would be required to implement CEI only as it introduces new enhanced services.… (Read More →)

1. In analog computing, a functional unit that compares two analog variables and indicates the result of that comparison.
2. A device that compares two items of data and indicates the result of that comparison.
3. A device for determining the dissimilarity of two items such as two pulse patterns or words.

1. The division of data into isolated blocks for the purpose of reducing risk; e.g., the isolation of the operating system, application software , and files from one another in a storage device in order to provide protection against unauthorized or concurrent access. [After 2382-pt.8]
2. A nonhierarchical grouping of sensitive information used to control access to data more finely… (Read More →)

The segregation of components, programs, and information to provide isolation.
Note: Compartmentation provides some protection against overall compromise, contamination, or unauthorized access.

1. [An] information systems (IS) mode of operation wherein each user with direct or indirect access to a system, its peripherals, remote terminals, or remote hosts has all of the following: (a) valid security clearance for the most restricted information processed in the system; (b) formal access approval and signed nondisclosure agreements for that information [to] which a user is… (Read More →)

Capability of two or more items or components of equipment or material to exist or function in the same system or environment without mutual interference. [JP 1-02]

Testing to be carried out to validate proper interworking of interconnecting network facilities and equipment. Compatibility tests are performed prior to cutover to validate functional capabilities and services provided over the interconnections. [T1.234-1993]

Independent sideband transmission in which the carrier is deliberately reinserted at a lower level after its normal suppression to permit reception by conventional AM receivers.
Note: Compatible sideband transmission is usually single-sideband (SSB) amplitude-modulation-equivalent (AME) transmission consisting of the emission of the carrier plus the upper sideband. Synonym amplitude modulation equivalent.

Signaling in which the transmission of each signal in the forward direction from an originating terminal is inhibited until an acknowledgement of the satisfactory receipt of the previous signal is received by the originating terminal.

A company that provides exchange access services in competition with an established U. S. telephone local exchange carrier.

In time-assignment speech interpolation (TASI) or digital speech interpolation (DSI), truncation of the initial part of a speech spurt, caused when all channels in a given direction of transmission are busy and the transmission of the spurt must wait for an available channel.

1. To translate a computer program expressed in a high-level language into a program expressed in a lower level language, such as an intermediate language, assembly language, or a machine language.
2. To prepare a machine language program from a computer program written in another programming language by making use of the overall logic structure of the program or by… (Read More →)

A computer program for compiling. Synonym compiling program.

Synonym compiler.

A group of conductors of the same general type (e.g., quadded, paired) within a single cable sheath. [47 CFR Pt.36-A]

1. With respect to additive mixing, any pair of colors that are radially opposite one another relative to the white point on a chromaticity chart, e.g., the familiar CIE chart.
Note: Complementary colors may be combined additively to produce the perception of white.
2. Analogous pairs of colors with respect to subtractive mixing.

A means for an enhanced-service provider customer to connect to a network and to the enhanced service provider.
Note: Complementary network services usually consist of the customer local service, such as a business or residence, and several associated service features, such as a call-forwarding service.

All groups of operator positions, wherever located, associated with the same call distribution and/or stored program control unit. [47 CFR Pt.36-A]

A one-time process to verify that a collection of software and hardware fulfills given specifications. [Mattila]

1. An assembly, or part thereof, that is essential to the operation of some larger assembly and is an immediate subdivision of the assembly to which it belongs.
Note: For example, a radio receiver may be a component of a complete radio set consisting of a combined transmitter-receiver, i.e., a transceiver. The same radio receiver could also be a subsystem… (Read More →)

See CAV.

The structure of a video signal wherein the R', G', and B' signals are kept separate from one another or wherein luminance and two bandlimited color-difference signals are kept separate from one another.
Note: The separation may be achieved by separate channels, or by time-division multiplexing, or by a combination of both. [After SMPTE]

A profile that is made up of a defined subset of a single standard [POSIX.0].

A communications cable having both optical and metallic signal-carrying components.
Note 1: A cable having optical fiber(s) and a metallic component, e.g., a metallic twisted pair, used solely for conduction of electric power to repeaters, does qualify as a composite cable.
Note 2: A cable having optical fiber(s), plus a metallic strength member or armor, does not qualify as a… (Read More →)

The structure of a video signal wherein the luminance and two bandlimited color-difference signals are simultaneously present in the channel.
Note: The format may be achieved by frequency-division multiplexing, quadrature modulation, etc. It is common to strive for integrity by suitable separation of the frequencies, or since scanned video signals are highly periodic, by choosing frequencies such that the chrominance… (Read More →)

Signaling in which an arrangement is made to provide direct current signaling and dial pulsing beyond the range of conventional loop signaling.
Note: Composite signaling, like DX signaling, permits duplex operation, i.e., permits simultaneous two-way signaling. Synonym CX signaling.

A signal consisting of horizontal sync pulses, vertical sync pulses, and equalizing pulses only. [After Silicon]

In television systems, a test signal consisting of a line bar (125 ns rise time and fall time), a 2T pulse (250 ns half-amplitude duration), a
1
2. 5T (
1. 5625 microseconds half-amplitude duration) chrominance pulse, and a five-riser staircase signal modulated by the color subcarrier having a peak-to-peak amplitude of 40 IRE units superimposed upon standard synchronizing and… (Read More →)

A test signal composed of two different frequencies and used for intermodulation distortion measurements.

See composite video signal.

The electrical signal that represents complete color picture information and all synchronization signals, including blanking and the deflection synchronization signals to which the color synchronization signal is added in the appropriate time relationship. [After IEEE] Synonym composite video.

A circuit that can be used simultaneously either for telephony and dc telegraphy or for telephony and signaling.
Note: Separation of the two may be accomplished by frequency discrimination. Synonym voice-plus circuit.

1. A document represented by a software file that is composed of more than one element; e.g., text, graphics, voice, video.
2. The software file itself.

In ac signaling, a signal consisting of the simultaneous transmission of more than one frequency.
Note: An example of compound signaling is dual-tone multifrequency (DTMF) signaling.

See data compaction, data compression, signal compression.

Video that has been encoded so as to reduce the number of bits required for storage or transmission.

See data compression, signal compression.

1. In signal compression, the ratio of the dynamic range of compressor input signals to the dynamic range of the compressor output signals.
Note: The compression ratio is usually expressed in dB. For example, a 40-dB input range compressed to a 30-dB output range would be equivalent to a 10-dB compression.
2. In digital facsimile, the ratio of the total… (Read More →)

A nonlinear analog device that has a lower gain at higher input levels than at lower input levels.
Note: A compressor is used to allow signals with a large dynamic range to be sent through devices or circuits with a smaller dynamic range.

1. The known or suspected exposure of clandestine personnel, installations, or other assets or of classified information or material, to an unauthorized person. [JP1]
2. The disclosure of cryptographic information to unauthorized persons.
3. The recovery of plain text of encrypted messages by unauthorized persons through cryptanalysis methods.
4. Disclosure of information to unauthorized persons or a violation of the… (Read More →)

In cryptography, a key state in which the secrecy or integrity of the key is suspect. [After X9.17/95]

Unintentional signals that, if intercepted and analyzed, would disclose the information transmitted, received, handled, or otherwise processed by information systems equipment. [INFOSEC]

1. A device that accepts data, processes the data in accordance with a stored program, generates results, and usually consists of input, output, storage, arithmetic, logic, and control units.
2. A functional unit that can perform substantial computation, including numerous arithmetic operations or logic operations, without human intervention during a run.
Note 1: This definition, approved by the Customs Council,… (Read More →)

1. In computer security, a willful or negligent unauthorized activity that affects or involves the computer security of a data processing system. [2382-pt.8]
2. In computer crime, the use of a computer to perform an illegal or unauthorized act.
3. Intentional or reckless misuse, alteration, disruption, or destruction of information processing resources. [INFOSEC-99]

Of a computer, the physical configuration, logical structure, formats, protocols, and operational sequences for processing data, controlling the configuration, and controlling the operations.
Note: Computer architecture may also include word lengths, instruction codes, and the interrelationships among the main parts of a computer or group of computers.

A communication session, facilitated by means of a computer network, between several participants, each of them having access to all messages submitted.
Note: Messages, in general, have no specified recipient, but are sent to the entire membership. Messages may contain text, video, audio, graphics, software, or a combination thereof. Some of these may be contained in the message and may… (Read More →)

1. Teleconferencing supported by one or more computers.
2. An arrangement in which access, by multiple users, to a common database is mediated by a controlling computer.
3. The interconnection of two or more computers working in a distributed manner on a common application process.

A violation of law committed with the aid of, or directly involving, a data processing system or network. [2382-pt.8]

Use of a crypto-algorithm program by a computer to authenticate or encrypt/decrypt information. [INFOSEC-99]

A fraud committed with the aid of, or directly involving, a data processing system or network. [2382-pt.8]

1. Graphics implemented through the use of computers.
2. Methods and techniques for converting data to or from graphic displays via computers.
3. The branch of science and technology concerned with methods and techniques for converting data to or from visual presentation using computers.

See cgm.

Synonym programming language.

1. A network of data processing nodes that are interconnected for the purpose of data communication.
2. A communications network in which the end instruments are computers.

See network engineering.

A specialized operating system designed for computer networking on minicomputers and microcomputers in a local networking area / campus area network.
Note: A NOS is usually designed to run on existing software designed for that computer and may require interface hardware for the workstation and server.

See peripheral equipment.

See program.

The address assigned to the initial storage location of a computer program in main storage.

See routine.

The discipline that is concerned with methods and techniques relating to data processing performed by automatic means.

1. Measures and controls that ensure confidentiality, integrity, and availability of information-system (IS) assets including hardware, software, firmware, and information being processed, stored, and communicated. [INFOSEC-99] Synonym automated information systems security.
2. The application of hardware, firmware and software security features to a computer system in order to protect against, or prevent, the unauthorized disclosure, manipulation, deletion of information or… (Read More →)

Hardware/software designed to provide computer security features in a larger system environment. [INFOSEC-99]

A functional unit, consisting of one or more computers and associated software, that (a) uses common storage for all or part of a program and also for all or part of the data necessary for the execution of the program, (b) executes user-written or user-designated programs, and (c) performs user-designated data manipulation, including arithmetic and logic operations.
Note: A computer… (Read More →)

The ability of a computer system to continue to operate correctly even though one or more of its components are malfunctioning.
Note: System performance, such as speed and throughput, may be diminished until the faults are corrected. Synonym computer system resilience.

Synonym computer system fault tolerance.

See systems design.

In computing, a group of bits or characters that occupies one or more storage locations and is treated by computers as a unit. Synonym machine word.

SeeCASE.

See CASE.

Synonym assembly language.

A programming language in which words and syntax are designed for use on a specific computer or class of computers. Synonymsmachine-oriented language.

An examination of the procedures used in a data processing system to evaluate their effectiveness and correctness, and to recommend improvements. [2382-pt.8]

Synonym computer system.

Acronym for communications security.

[The] definable perimeter encompassing all hardware, firmware, and software components performing critical COMSEC functions, such as key generation and key handling and storage. [INFOSEC-99]

[A] collection of NSA-approved microchips. [INFOSEC-99]

Computer instructions or routines controlling or affecting the externally performed functions of key generation, key distribution, message encryption/decryption, or authentication. [INFOSEC-99]

Equipment or a combination of components ready for use in a COMSEC application. [INFOSEC-99]

Equipment designed to provide security to telecommunications by converting information to a form unintelligible to an unauthorized interceptor and, subsequently, by reconverting such information to its original form for authorized recipients; also, equipment designed specifically to aid in, or as an essential element of, the conversion process.
Note: COMSEC equipment includes crypto-equipment, crypto-ancillary equipment, cryptoproduction equipment, and authentication equipment. [INFOSEC]

COMSEC incident that has been investigated, evaluated, and determined to jeopardize the security of COMSEC material or the secure transmission of information. [INFOSEC-99]

[An] item designed to secure or authenticate telecommunications.
Note: COMSEC material includes, but is not limited to, key, equipment, devices, documents, firmware or software that embodies or describes cryptographic logic and other items that perform COMSEC functions. [INFOSEC-99]

[A] removable component that performs COMSEC functions in a telecommunications equipment or system. [INFOSEC-99]

[The] act of listening to, copying, or recording transmissions of one's own official telecommunications to analyze the degree of security. [INFOSEC-99]

[A] statement of COMSEC measures and materials used to protect a given operation, system, or organization. [INFOSEC-99]

[An] organized collection of COMSEC and communications information relative to a given operation, system, or organization. [INFOSEC-99]

Information required by a COMSEC equipment or system to enable it to properly handle and control key. [INFOSEC-99]

Central office equipment whose function is to concentrate traffic from subscriber lines onto a lesser number of circuits between the remotely located concentration equipment and the serving central office concentration equipment. This concentration equipment is connected to the serving central office line equipment. [47 CFR Pt.36-A]

1. In data transmission, a functional unit that permits a common path to handle more data sources than there are channels currently available within the path.
Note: A concentrator usually provides communication capability between many low-speed, usually asynchronous channels and one or more high-speed, usually synchronous channels. Usually different speeds, codes, and protocols can be accommodated on the low-speed side.… (Read More →)

In an optical fiber, the distance between the center of the two concentric circles that specify the cladding diameter and the center of the two concentric circles that specify the core diameter.
Note: The concentricity error is used in conjunction with tolerance fields to specify or characterize optical fiber core and cladding geometry. Synonyms core eccentricity, core-to-cladding concentricity, core-to-cladding eccentricity,… (Read More →)

An off-hook condition applied to the network interface (NI) by the network that indicated the network intends to complete a call attempt to the customer installation (CI) or intends to continue an established connection. [T1.208-1989]

Those aspects of the rules used in the formal specification of data that embody a specific representation of those data. [T1.208-1989]

1. Synonym multitasking.
2. In data link operations, the operation in which two or more data links are used during the same, usually short, time interval, while adhering to the protocols of each link without providing data forwarding among the links.

A mechanism that is used to protect and control the viewing of traditional broadcast TV content, on-demand content, and pay-per-view. It has been implemented over uni-directional and bi-directional networks and co-channel transport. It is used both in analog TV broadcast systems and in digital TV delivery systems (where the equivalent of analog de-scrambling for digital services is implemented).

Synonym non-return-to-zero mark.

A communications circuit optimized to obtain desired characteristics for voice or data transmission.

A form of diphase modulation, combined with signal conditioning, that (a) eliminates the dc component of the signal, (b) enhances timing recovery, and (c) facilitates transmission over voice frequency (VF) circuits or coaxial cables.

A loop that has conditioning equipment to obtain the desired line characteristics for voice or data transmission.
Note: The conditioning equipment is used to improve the amplitude-vs. -frequency characteristics of the circuit and to match impedance.

1. At junctions of circuits, equipment used to obtain desired circuit characteristics, such as matched transmission levels, matched impedances, and equalization between facilities.
2. Corrective networks used to improve data transmission, such as equalization of the insertion-loss-vs. -frequency characteristic and the envelope delay distortion over a desired frequency range.

1. Interference resulting from noise or unwanted signals entering a device by conductive coupling, i.e., by direct coupling.
2. An undesired voltage or current generated within, or conducted into, a receiver, transmitter, or associated equipment, and appearing at the antenna terminals.

1. In a semiconductor, the range of electron energy, higher than that of the valence band, sufficient to make the electrons free to move from atom to atom under the influence of an applied electric field and thus constitute an electric current.
2. In the atomic structure of a material, a partially filled or empty energy level in which electrons… (Read More →)

Energy transfer achieved by means of physical contact, i.e., coupling other than inductive or capacitive coupling.
Note 1: Conductive coupling may be achieved by wire, resistor, or common terminal, such as a binding post or metallic bonding.
Note 2: Conductive coupling passes the full spectrum of frequencies, including dc. Synonym direct coupling.

Synonym antenna blind cone.

Acronym for connectivity exchange.

In conference calling, the state in which conference resources have been allocated to the specified conference and at least one party has a connection to the conference. That connection could be either active or held. [T1.647-1995]

A service feature that allows a call to be established among three or more stations in such a manner that each of the stations is able to communicate with all the other stations. Synonym multiple call.

In audio and video teleconferences, the user in charge of the conference when the service is invoked and the conference reaches the active state.
Note: The conference controller may perform any or all of the following actions: drop, floating, isolate, reattach, and split. [After T1.647-1995] Synonym [loosely] moderator.

In conference calling, the state in which the conference is active but without a controller. This state is possible when two or more conferees exist on an active conference and the controller successfully disconnects himself/herself. [T1.647-1995]

In conference calling, the served user's (or controller's) reference to the conference itself. [T1.647-1995]

In conference calling, the state prior to the receipt of a "conference invocation request," or after a particular conference has ended. [T1.647-1995]

In a communications network, operation that allows a call to be established among three or more stations in such a manner that each of the stations is able to communicate directly with all the other stations.
Note: In radio systems, the stations may receive simultaneously, but must transmit one at a time. The common operational modes are "push-to-talk" for telephone… (Read More →)

A measure of the security of a trusted function, or a set of trusted functions, as calculated by a competent authority [CESG].
Note: For HMG purposes, the Head of the Certification Body of the UK Scheme is the "competent authority". See also: Assurance, Confidence Level .

A measure of confidence as described in CESG Computer Security Memorandum No.3 - "UK Systems Security Confidence Levels" [CESG].
Note: ITSEC uses the term "assurance" rather than "confidence".

1. Of classified or sensitive data, the degree to which the data have not been compromised; i.e., have not been made available or disclosed to unauthorized individuals, processes, or other entities. [After 2382-pt.8]
2. Assurance that information is not disclosed to unauthorized persons, processes, or devices. [INFOSEC-99]
3. A property by which information relating to an entity or party is… (Read More →)

1. In a communications or computer system, an arrangement of functional units according to their nature, number, and chief characteristics.
Note 1: Configuration pertains to hardware, software, firmware, and documentation.
Note 2: The configuration will affect system performance.
2. Selection of one of the sets of possible combinations of features of a system[FC Ver
1. 0 Dec 1992].
3. The… (Read More →)

Documentation that formally defines the configuration items of a system [CESG].

1. After establishing a configuration, such as that of a telecommunications or computer system, the evaluating and approving changes to the configuration and to the interrelationships among system components.
2. In distributed-queue dual-bus (DQDB) networks, the function that ensures the resources of all nodes of a DQDB network are configured into a correct dual-bus topology.
Note: The functions that are… (Read More →)

A measure of the security of a trusted function, or a set of trusted functions, as calculated by a competent authority [CESG].
Note: For HMG purposes, the Head of the Certification Body of the UK Scheme is the "competent authority". See also: Assurance, Confidence Level .

1. [The] management of security features and assurances through control of changes made to hardware, software, firmware, documentation, test, test fixtures, and test documentation throughout the life cycle of an information system (IS). [INFOSEC-99]
2. The control of changes--including the recording thereof--that are made to the hardware, software, firmware, and documentation throughout the system life cycle.
3. The procedure by… (Read More →)

Group of people responsible for the management of changes to a system, to include assessment of their impact on security.
Note: The certifier should be represented on the Configuration Management Board for a certified system [CESG].

The prevention of information flow [CESG].

Signaling that ensures error-free transmission of dialed information by returning a unique digit-dependent signal from the far end as each digit is sent over a trunk.

In facsimile, a signal from a CCITT Group 1, 2, or 3 facsimile receiver, indicating it is ready to receive picture signals.

A test performed by an independent body to determine if a particular piece of equipment satisfies the criteria in a specified controlling document, such as a Federal standard, an American National Standard, a Military Standard, or a Military Specification.

1. In a communications switch, a state or condition that occurs when more subscribers attempt simultaneously to access the switch than it is able to handle, even if unsaturated.
2. In a saturated communications system, the condition that occurs when an additional demand for service occurs.

A local variable of a node that indicates the number of blocks to be dropped from packets containing droppable blocks (0, 1, 2, or 3 blocks may be specified). [T1.312-1991]

An off-hook condition applied to the network interface (NI) by the network that indicated the network intends to complete a call attempt to the customer installation (CI) or intends to continue an established connection. [T1.405-1989]

The amount of time that a terminal (client) is being served by a network. [Bahorsky]
Note: Connect time can refer to either the total amount of time that the terminal is connected to the network or just the amount of time that the terminal actually transmits or receives data.

In the public switched telephone networks, the equipment provided by a common carrier to accomplish electrical interconnection between customer-provided equipment and the facilities of the common carrier.

1. A provision for a signal to propagate from one point to another, such as from one circuit, line, subassembly, or component to another.
2. An association established between functional units for conveying information.
3. A temporary concatenation of transmission channels or telecommunication circuits, switching and other functional units set up to provide a route for a transfer of information… (Read More →)

The set of functions used for setting up, maintaining, and releasing a communication path between two or more users or a user and a network entity, e.g., a dual-tone multifrequency receiver. [T1.667-1999]

A terminating device at one end of a layer connection within a service access point (SAP). [After T1.627-1993]

The establishment of the capability for the transmission of user information. [T1.507-1996]

A number that identifies unambiguously a certain connection at the interface between the signaling connection control plan (SCCP) and a user function. [T1.110-1987]

See connection-oriented mode transmission, connection-oriented network service.

A call control signal at the data circuit-terminating-equipment/data-terminal-equipment (DCE/DTE) interface that indicates to the DTE that the establishment of the data connection is in progress and that the ready-for-data signal will follow.

The product of (a) the number of messages and, (b) the average minutes of connection per message. [47 CFR Pt.36-A]

See connection-oriented mode transmission.

A data-transfer protocol in which a logical connection is established between end user terminals.

1. In a packet-switched network, a mode of transmission in which there is a complete information transfer transaction for each packet or group of packets, i.e., the information transfer phase is preceded by an access phase and followed by a disengagement phase.
Note 1: During the information transfer phase of connection-oriented mode transmission, more than one packet may be transmitted.… (Read More →)

A network service that establishes logical connections between end users before transferring information. [T1.110-1987]

See connectionless mode transmission.

1. In a packet-switched network, transmission in which each packet is encoded with a header containing a destination address sufficient to permit the independent delivery of the packet without the aid of additional instructions.
Note 1: A packet transmitted in a connectionless mode is frequently called a datagram.
Note 2: In connectionless mode transmission of a packet, the service provider… (Read More →)

A network service that transfers information between end users without establishing a logical connection or virtual circuit between those specific users. [After T1.110-1987]

A service that allows the transfer of information among subscribers without the need for end-to-end establishment procedures. [T1.629-1999]

See connectionless mode transmission.

1. A unit of traffic measurement expressed as the number of connections established at a switching point per hour.
2. A unit of traffic measurement used to express the rate at which circuits are established at a switch.
Note: The magnitude of the CCH is an instantaneous value subject to change as a function of time, i.e., from moment to… (Read More →)

For nodes (or links), the minimum number of nodes (or links) whose removal results in losing all paths that can be used to transfer information from a source to a sink. [T
1. Rpt24-1993]

In an adaptive or manually operated high-frequency (HF) radio network, the automatic or manual exchange of information concerning routes to stations that are not directly reachable by the exchange originator.
Note: The purpose of the exchange is to identify indirect paths and/or possible relay stations to those stations that are not directly reachable.

A device for mating and demating electrical power connections or communications media.
Note: A connector is distinguished from a splice, which is a permanent yyjoint.

A basic principle of optics, that no passive optical system can increase the quantity L/n2, where L is the radiance of a beam and n is the local refractive index.
Note: "Conservation of radiance" was formerly called "conservation of brightness" or the "brightness theorem. "

A carrier authorized to provide telecommunications services both within and outside World Zone 1 using the yyNorth American Numbering Plan (NANP)and the international dialing plan, respectively. [T1.104-1988]

Local communications service provided by GSA to all Federal agencies located in a building, complex, or geographical area.

In video, an image coding system that derives a luminance signal and two bandwidth-limited color-difference signals, to provide luminance information that is encoded into one signal supplemented by, but totally independent of, two color signals carrying only chrominance information, i.e., hue and saturation.
Note 1: Constant luminance is only achieved when the luminance and chrominance vectors are derived from linear… (Read More →)

The process of creating a Target of Evaluation [ITSEC].

A service feature that allows a speaker on an extension instrument to place one call on hold and to speak with another caller on a separate line.

A term used to denote either an IPTV Subscriber or an IPTV User (see also IPTV Consumer).

The domain where the IPTV services are consumed. In the consumer domain, a single terminal may be used for service consumption, but also a network of terminals and related devices may be present for this purpose. The domain may also be a mobile end device in this case the delivery system of a network provider is a wireless Wide Area… (Read More →)

A device within the Consumer Domain such as an ITF or a DNG.

1. The introduction of data of one security [classification or] security category into data of a lower security classification or different security category. [2382-pt.8] [INFOSEC-99].
2. Relative to numbering guidelines and FCC regulations, contamination occurs when at least one telephone number within a thousands-block of telephone numbers is not available for assignment to end users or customers. Blocks contaminated up… (Read More →)

1. In Web terminology, the text, media, and links or information displayed by a browser at a particular Web site.
2. Electronic or mechanical representation, in analog or digital form, of audiovisual data consisting of individually or in composite form still or moving images, audio, text, or graphics to include related data and metadata.

The nested units of information into which a media stream can be decomposed. [T1.80
1. 04-1997]

Storage and management of databases by a content provider. [2382-pt.35]

A rating provided by a rating service that defines or categorizes the contents of a Web site. [Bahorsky]

A generalized form of Video on Demand that encompasses both video and non-video content.

A combination of Access Control and Copy Control.

1. An organization that creates and maintains databases containing information from an information provider.
Note: The content provider and the information provider may be the same organization.
2. The entity that owns or is licensed to sell content or content assets. Although the Service Provider is the primary source for the customer at home, a direct logical information flow may… (Read More →)

Synonym associative storage.

1. A condition that arises when two or more data stations attempt to transmit at the same time over a shared channel, or when two data stations attempt to transmit at the same time in two-way alternate communication.
Note: A contention can occur in data communications when no station is designated a master station. In contention, each station must monitor… (Read More →)

The sharing or synchronization of other information associated with a service, such as application state or security context.

Information derived from the context in which an access is made (e.g., time of day) [10181-3].

[A] key held for use under specific operational conditions or in support of specific contingency plans. [INFOSEC-99]

1. A plan for backup procedures, emergency response, and post-disaster recovery. Synonym disaster recovery plan. [2382-pt.8]
2. [A] plan maintained for emergency response, backup operations, and post-disaster recovery for an information system (IS), to ensure the availability of critical resources and to facilitate the continuity of operations in an emergency situation. [INFOSEC-99]

A procedure that is an alternative to the normal path of a process if an unusual but anticipated situation occurs. [2382-pt.8]

A check made of a circuit to verify that a communication or power path exists.

A device that is used to interconnect the Go and Return paths of a circuit at the incoming end, and through which the detection of an incoming check tone transmits another check tone to permit a continuity checking of a 2-wire circuit. [After T1.110-1987] Synonym [loosely] smart jack.

1. Operation in which certain components, such as nodes, facilities, circuits, or equipment, are in an operational state at all times.
Note: Continuous operation usually requires that there be fully redundant configuration, or at least a sufficient X out of Y degree of redundancy for compatible equipment, where X is the number of spare components and Y is the number… (Read More →)

In teleconferencing, the concurrent presence of two or more video images, such as two images that may appear on a single monitor on a split screen or on two separate monitors.

A characteristic of an image (e.g., a photograph) such that the image has all the values (0 to 100%) of gray (black and white) or color in it.
Note: A continuous tone can be approximated by the use of thousands or millions of gradations of black and white or colors. The granularity of computer screens (viz. , pixel size) can… (Read More →)

In facsimile, an object, i.e., an original, or a recorded copy, that contains shades of gray, i.e., contains densities between black and white, such as in a photographic print.

A wave of constant amplitude and constant frequency.

A type of delta modulation in which the size of the steps of the approximated signal is progressively increased or decreased as required to make the approximated signal closely match the input analog wave.

In digital facsimile, density step lines in the recorded copy resulting from analog-to-digital conversion when the object, i.e., the original, has observable shades of gray between the smallest density steps of the digital system.

1. In display systems, the relation between the intensity of color or brightness of an area occupied by an element or an image and the intensity of the area not occupied by that element or image. Deprecated synonym brightness ratio.
2. In optical character recognition, the difference between color or shading of the printed material on a document and the… (Read More →)

In B-ISDN applications, the use of broadband transmission of audio or video information to the user for post-production processing and distribution.

A collection of control attributes associated with a security object [ECMA138].

1. Attributes, associated with a security object, that when matched against the privilege attributes of a security subject, are used to grant or deny access to the security object [ECMATR46].
2. Attributes associated with an object that, when matched against security attributes of a subject, are used to grant or deny access to that object [POSIX.6].

Synonym trackball.

A character that initiates, modifies, or stops a function, event, operation, or control operation.
Note: Control characters may be recorded for use in subsequent actions. They are not graphic characters but may have a graphic representation in some circumstances.

The branch of technology devoted to the design, development, and application of communications facilities used specifically for control purposes, such as for controlling (a) industrial processes, (b) movement of resources, (c) electric power generation, distribution, and utilization, (d) communications networks, and (e) transportation systems.

In a protocol data unit (PDU), the field that (a) contains data interpreted by the receiving destination logical-link controller (LLC) and (b) may be the field immediately following the destination service access point (DSAP) and source service access point (SSAP) address fields of the PDU.

Synonym control operation.

1. In computers and networks, the device that displays the progress or status of the overriding software or procedures.
2. In video production, a display device used primarily for decisions on subject matter, composition, and sequences to be selected in real time. [After SMPTE]
3. In robotics, a visual device used to view the work of robots or to view… (Read More →)

1. Measures taken to minimize unintended electromagnetic radiation emanating from a system or component and to minimize electromagnetic interference.
Note: Control of electromagnetic radiation is exercised for purposes of security and the reduction of interference, especially on ships and aircraft.
2. A national operational plan to minimize the use of electromagnetic radiation in the United States and its possessions and… (Read More →)

An operation that affects the recording, processing, transmission, or interpretation of data.
Note: Examples of control operations include starting and stopping a process; executing a carriage return, a font change, or a rewind; and transmitting an end-of-transmission (EOT) control character. Synonym control function.

1. In a communications network, the station that selects the master station and supervises operational procedures, such as polling, selecting, and recovery.
Note: The control station has the overall responsibility for the orderly operation of the entire network.
2. A fixed station whose transmissions are used to control automatically the emissions or operations of another radio station at a specified… (Read More →)

The magnetized portion along the length of a videotape on which synchronous control information is placed; the control track contains a pulse for each video field and is used to synchronize the tape and the video signal. [After Silicon]

Access in which the resources of an area or system is limited to authorized personnel, users, programs, processes, or other systems, and denied to all others.

1. An area (a) in which uncontrolled movement will not result in compromise of classified information, (b) that is designed to provide administrative control and safety, or (c) that serves as a buffer for controlling access to limited-access areas.
2. An area to which security controls have been applied to protect an information-processing system's equipment and wirelines, equivalent to that… (Read More →)

Secure telecommunications or information handling equipment, or associated cryptographic component, that is unclassified but governed by a special set of control requirements. Such items are marked "CONTROLLED CRYPTOGRAPHIC ITEM" or, where space is limited, "CCI. " [INFOSEC-99]

A signal, sent in the backward direction, to indicate that a call cannot be completed because the called line is not in a ready condition, but is under control, as opposed to not being in a ready condition and not under control.

A procedure of transferring, in a controlled way, signaling traffic from an alternative signaling route to the normal signaling route when the latter becomes available. [T1.226-1992]

See controlled security operation, multilevel security.

In a communications system, operation in which (a) internal security controls prevent inadvertent disclosures, (b) personnel, physical, and administrative controls are used to prevent unauthorized access, (c) both cleared and uncleared users are serviced, and (d) if required, both secured and unsecured remote terminal areas are serviced.

[A] condition existing when access control is applied to all users and components of an information system (IS). [INFOSEC-99]

Three-dimensional space surrounding information-system (IS) equipment, within which unauthorized persons are denied unrestricted access and are either escorted by authorized persons or are under continuous physical or electronic surveillance. [INFOSEC-99] Synonym restricted area.

In an automated radio, the device that commands the radio transmitter and receiver, and that performs processes, such as automatic link establishment, channel scanning and selection, link quality analysis, polling, sounding, message store and forward, address protection, and anti-spoofing.

[In cryptosystems, the] official responsible for directing the operation of a cryptonet and for managing the operational use and control of keying material assigned to the cryptonet. [INFOSEC-99]

1. In a tristimulus color monitor (i.e., CRT) that employs phosphors excited (driven) by one or more electron beams, the process of controlling the beam(s) to ensure that the individual phosphors representing the color elements within each pixel are properly driven so that (a) within a given pixel there is a proper color balance to ensure the illusion of white,… (Read More →)

A network point at which two or more possible routes through different intermediate networks from the origination network to destination network converge. A convergence point may occur in any network except the origination network. A convergence point for a message transiting in one direction is a branch point for a message transiting in the opposite direction. [T1.118-1992]

The product of (a) the number of messages and, (b) the average minutes of conversation per message. [47 CFR Pt.36-A]

The product of (a) the number of messages, (b) the average minutes of conversation per message, and (c) the average route kilometers of circuits involved. [47 CFR Pt.36-A]

Seechat.

A mode of communication analogous to a conversation between two persons.

In telecommunications, a service that provides two-way, interactive, real-time, end-to-end information transfer.

The actual agreed upon scheduled date and time to commence cutover in a coordinated conversion.

A type of error-correction code in which (a) each m-bit information symbol (each m-bit string) to be encoded is transformed into an n-bit symbol, where n>m and (b) the transformation is a function of the last k information symbols, where k is the constraint length of the code.
Note: Convolutional codes are often used to improve the performance of radio… (Read More →)

In a land or maritime convoy, communications (a) that is among the elements of the convoy, (b) includes radio, visual, and sound transmissions, (c) in which radio intervehicle or intership communications are usually by radiotelephone using the receipt method of operation, (d) in which the convoy commander vehicle or ship usually has the net-control station aboard and (e) that usually… (Read More →)

1. A small piece of information that is automatically stored on a client computer by a Web browser and referenced to identify repeat visitors to a Web site and to tailor information in anticipation of the visitor's interests.
Note: Some privacy advocates have objected to the use of cookies without a user's consent. [After Bahorsky]
2. A general mechanism that… (Read More →)

In facsimile systems, the product of the total scanning length and the scanning density, given by CF = L, where L is the scanning line length and is the scanning line density, both in compatible units.
Note: For example, a 20-cm line and a line density of 6 scanning pitches per centimeter would yield a cooperation factor of 120.

Electronically exchanging functions of locally generated, random components, from which both terminals of a secure circuit construct traffic encryption key or key encryption key for use on that circuit. [INFOSEC-99]

Synonym manual remote rekeying.

One of a set of clocks distributed over a spatial region, producing time scales that are synchronized to the time scale of a reference clock at a specified location.

A process whereby a portion of the equipment or facilities from an existing service is to be reused in a replacement service.

A time scale synchronized within given tolerances to a reference time scale.

Time scale based on the second (SI), as defined and recommended by the CCIR, and maintained by the Bureau International des Poids et Mesures (BIPM). For most practical purposes associated with the Radio Regulations, UTC is equivalent to mean solar time at the prime meridian (0° longitude), formerly expressed in GMT. [NTIA] [RR]
Note 1: The maintenance by BIPM includes… (Read More →)

The area associated with an Earth station outside of which a terrestrial station sharing the same frequency band neither causes nor is subject to interfering emissions greater than a permissible level. [NTIA] [RR]

1. The line enclosing the coordination area. [NTIA] [RR]
2. The perimeter of the coordination area.

1. Distance on a given azimuth from an Earth station beyond which a terrestrial station sharing the same frequency band neither causes nor is subject to interfering emissions greater than a permissible level. [NTIA] [RR]
2. For the purpose of this part [of 47CFR], the expression "coordination distance" means the distance from an earth station, within which there is a… (Read More →)

1. To receive a message.
2. A recorded message or a duplicate of it.
3. To read data from a source, leaving the source data unchanged at the source, and to write the same data elsewhere, though they may be in a physical form that differs from that of the source.
4. To understand a transmitted message.

The enforcement of conditions under which copyrighted content can be copied. Copy Control is one part of Content Protection.

A mechanism used to protect content from being copied in an unauthorized manner via analog and/or digital IPTV Receiving Device interfaces.

A radio- or video-communications watch in which an operator is required to maintain a continuous receiver watch and to keep a complete log.

Of a data medium such as a diskette, pertaining to the use of one or more schemes designed to thwart copying in violation of copyright law or security considerations.

Common Object Request Broker Architecture

A switchboard circuit in which a plug-terminated cord is used to establish connections manually between user lines or between trunks and user lines.
Note: A number of cord circuits are furnished as part of the switchboard position equipment. The cords may be referred to as front cord and rear cord or trunk cord and station cord. In modern cordless switchboards,… (Read More →)

The lamp associated with a cord circuit that indicates supervisory conditions for the respective part of the connection.

A telephone switchboard in which manually operated keys are used to make connections.

1. The central region about the longitudinal axis of an optical fiber, which region supports guiding of the optical signal.
Note 1: For the fiber to guide the optical signal, the refractive index of the core must be slightly higher than that of the cladding.
Note 2: In different types of fibers, the core and core-cladding boundary function slightly differently… (Read More →)

The part of the cross-sectional area of an optical fiber within which the refractive index is everywhere greater than that of the innermost homogeneous cladding, by a specified fraction of the difference between the maximum refractive index of the core and the refractive index of the innermost cladding.
Note 1: Artifacts of the manufacturing process, such as refractive index dip,… (Read More →)

In the cross section of a realizable optical fiber, ideally circular, but assumed to a first approximation to be elliptical, the average of the diameters of the smallest circle that can be circumscribed about the core-cladding boundary, and the largest circle that can be inscribed within the core-cladding boundary.

A printout, usually in hexadecimal characters, of the contents of core memory.
Note: A core dump is useful for analyzing an abnormally terminated computer run or finding bugs in a computer program.

Synonym concentricity error. See ovality.

Historically, one of a set of gateways (routers) operated by the Internet Network Operations Center at BBN.
Note: The core gateway system forms a central part of Internet routing in that all groups must advertise paths to their networks from a core gateway, using the exterior gateway protocol (EGP). [Bahorsky]

See ovality.

See magnetic core storage.

See concentricity error.

Synonym concentricity error.

Synonym concentricity error.

Synonym concentricity error.

1. A reflector consisting of three mutually perpendicular intersecting conducting flat surfaces, which returns a reflected electromagnetic wave to its point of origin.
Note: Such reflectors are often used as radar targets.
2. A directional antenna using two mutually intersecting conducting flat surfaces.
3. A device, normally consisting of three metallic surfaces or screens perpendicular to one another, designed to… (Read More →)

See corner reflector.

The set of laws, rules and practices that regulate how assets including the sensitive information are managed, protected and distributed within a user organization [ITSEC].

See CREN.

1. Maintenance actions carried out to restore a defective item to a specified condition.
2. Tests, measurements, and adjustments made to remove or correct a fault.

A property of a representation of a Target of Evaluation such that it accurately reflects the stated security target for that system or product [ITSEC].

A mathematical proof of consistency between a specification and its implementation. [INFOSEC-99]

Peer entities with a lower layer connection among them. [T1.629-1999]

class of service

Abbreviation for Cooperation for Open Systems Interconnection Networking in Europe.
Note: COSINE is a program sponsored by the European Commission, aimed at using OSI (Open Systems Interconnection) to tie together European research networks. [After Bahorsky]

Synonym Lambert's cosine law.

Collocation of electronic equipment on the same vehicle, station, or base.
Note: Equipment so located is often subject to interference because of its proximity to other equipment.

Random noise that originates outside the Earth's atmosphere.
Note: Cosmic noise characteristics are similar to those of thermal noise. Cosmic noise is experienced at frequencies above about 15 MHz when highly directional antennas are pointed toward the Sun or to certain other regions of the sky such as the center of the Milky Way Galaxy. Synonym galactic radio noise.

A phase-locked loop used for carrier phase recovery from suppressed-carrier modulation signals, such as from double-sideband suppressed carrier signals.
Note: In the usual implementation of a Costas loop, a local voltage-controlled oscillator provides quadrature outputs, one to each of two phase detectors, i.e., product detectors. The same phase of the input signal is also applied to both phase detectors and… (Read More →)

Central Office Terminal

Commercial Off-The Shelf

The universal law of attraction and repulsion of electric charges.

1. [An] action, device, procedure, technique, or other measure that reduces the vulnerability of an information system (IS). [INFOSEC-99]
2. Synonymous with Security Measure[CESG].

A conductor or system of conductors used as a substitute for earth or ground in an antenna system. [From Weik '89]

1. In international direct telephone dialing, a code that consists of 1-, 2-, or 3-digit numbers in which the first digit designates the region and succeeding digits, if any, designate the country (click here for a list).
2. In international record carrier transmissions, a code consisting of 2- or 3-letter abbreviations of the country names, or 2- or 3-digit numbers… (Read More →)

A conductor used to extend the ground at an approved building entrance facility to certain types of ac-powered equipment.

1. In fiber optics, a mode that shares energy among one or more other modes, all of which propagate together. [After 2196]
Note: The distribution of energy among the coupled modes changes with propagation distance.
2. In microwave transmission, a condition where energy is transferred from the fundamental mode to higher order modes.
Note: Energy transferred to coupled modes is… (Read More →)

Seedirectional coupler.

The desirable or undesirable transfer of energy from one medium, such as a metallic wire or an optical fiber, to another like medium, including fortuitous transfer.
Note: Examples of coupling include capacitive (electrostatic) coupling, inductive (magnetic) coupling, conducted (resistive or hard-wire) coupling, and fiber-optic coupling.

A number that expresses the degree of electrical coupling that exists between two circuits.
Note: The coupling coefficient is calculated as the ratio of the mutual impedance to the square root of the product of the self-impedances of the coupled circuits, all impedances being expressed in the same units.

In fiber optics, the efficiency of optical power transfer between two optical components. [After 2196]
Note 1: The transfer may take place (a) between an active component, such as an LED, and a passive component, such as an optical fiber, or (b) between two passive components such as two optical fibers.
Note 2: Coupling efficiency is usually expressed as the… (Read More →)

1. The loss that occurs when energy is transferred from one circuit, circuit element, or medium to another.
Note: Coupling loss is usually expressed in the same units--such as watts or dB--as in the originating circuit element or medium.
2. In fiber optics, the power loss that occurs when coupling light from one optical device or medium to another. [After… (Read More →)

The technique of concealing or altering the characteristics of communications patterns for the purpose of denying an unauthorized receiver information that would be of value; a process of modulo two addition of a pseudorandom bit stream generated by a cryptographic device with bits from the control message.

In radio communications, the geographical area within which service from a radio communications facility can be received.

1. A transmission channel that may be used to transfer data in a manner that violates security policy. [2382-pt.8]
2. [An] unintended and/or unauthorized communications path that can be used to transfer information in a manner that violates an information system (IS) security policy. [INFOSEC-99]
3. A channel which allows information to flow in violation of the System Security policy.… (Read More →)

1. [A] covert channel involving the direct or indirect writing to a storage location by one process and the direct or indirect reading of the storage location by another process. Covert storage channels typically involve a finite resource (e.g., sectors on a disk) that is shared by two subjects at different security levels. [INFOSEC-99]
2. A covert channel that involves… (Read More →)

1. [A] covert channel in which one process signals information to another process by modulating its own use of system resources (e.g., CPU time) in such a way that this manipulation affects the real response time observed by the second process. [INFOSEC-99]
2. A covert channel in which one process signals information to another by modulating its own use of… (Read More →)

Cellular on Wheels or Cellular on Wings

1. Customer Premises,
2. Content Protection.

Content Protection and Copy Management

Content Provider Domain

Abbreviation for customer premises equipment.

A dedicated facility between a network switch and a subscriber termination. [T1.207-2000]

The common facility between a network switch and a CPE switch. [T1.207-2000]

Abbreviation for characters per inch.

Common Presence and Instant Messaging

Coherent Passive Optical Network

1. Abbreviation for characters per second.
Note: Formerly, abbreviation for cycles per second, the unit used to express frequency. However, the hertz (Hz),an SI unit, is now the internationally accepted unit of frequency.
2. Abbreviation for cellular priority service.

Abbreviation forcentral processor.
3. Abbreviation for communications processor unit. A computer embedded in a communications system, i.e., the portion of a digital communications switch that executes programmed instructions, performs arithmetic and logical operations on signals, and controls input/output functions.

Abbreviation for channel reliability, circuit reliability.

1. Hacker jargon to indicate "one who breaks security on a system. "
Note: The term cracker was coined ca.1985 by hackers in defense against journalistic misuse of the term hacker.
2. An individual who, with malicious intent, gains or tries to gain illegal access to computers or computer programs. [After Bahorsky] Synonym password cracker.

Synonyms droid, Web crawler, Web spider.

Abbreviation for cyclic redundancy check.

1. A subset of access permissions (developed with the use of media-independent data) attesting to, or establishing, the identity of an entity, such as a birth certificate, driver's license, mother's maiden name, social security number, fingerprint, voice print, or other biometric parameter(s). [After X9.69]
2. [In security], information, passed from one entity to another, used to establish the sending entity's… (Read More →)

Abbreviation forCorporation for Research and Educational Networking. The organization resulting from the merger of BITNET and the academic computer network CSNET. [Bahorsky]

The peak-to-rms voltage ratio of an alternating current (ac) signal. [T1.401-1988]

In geometric optics, at a refractive boundary, the smallest angle of incidence at which total internal reflection occurs.
Note 1: The angle of incidence is measured with respect to the normal at the refractive boundary.
Note 2: The critical angle is given by where _c is the critical angle, n₁ is the refractive index of the less dense medium, and… (Read More →)

An operational area that requires specific environmental control because of the equipment or information contained therein.

1. In radio propagation by way of the ionosphere, the limiting frequency at or below which a wave component is reflected by, and above which it penetrates through, an ionospheric layer.
2. At vertical incidence, the limiting frequency at or below which incidence, the wave component is reflected by, and above which it penetrates through, an ionospheric layer.
Note: The… (Read More →)

1. Elements of a system that are so vital that disabling any of them would incapacitate the entire system.
2. [In security,] those physical and cyber-based systems essential to the minimum operations of the economy and government. [INFOSEC-99]

A mechanism within a Target of Evaluation whose failure would create a security weakness [ITSEC].

Synonym essential service.

That part of the total technical power load required for synchronous communications and automatic switching equipment.

The free-space wavelength that corresponds to the critical frequency.
Note: The critical wavelength is equal, in meters, to the speed of light (3 × 108 m/s) divided by the critical frequency in hertz.

Abbreviation for certificate revocation list. In cryptography, a list of revoked certificates.

Customer Relationship Management

An assembler that can run symbolic-language input on one type of computer and produce machine-language output for another type of computer.

An authentication method used by one certificate authority (CA) to certify any CA other than a CA immediately adjacent to it in a hierarchy (i.e., a superior or subordinate CA). [After X9.57]

The coupling of a signal from one channel, circuit, or conductor to another, where it is usually considered to be an undesired signal.

Intermodulation caused by the modulation of the carrier of a desired signal by an undesired signal.

A check made across the exchange to verify that an acceptable speech path exists. [T1.226-1992]

A radiotelegraph network operational procedure in which calling stations, such as ship stations, call other stations, such as shore stations, using one frequency, and then shift to another frequency to transmit their messages; the called stations answer using a third frequency.

Synonym cross-connection.

Connections between terminal blocks on the two sides of a distribution frame, or between terminals on a terminal block.
Note: Connections between terminals on the same block are also called straps. Synonyms cross-connect, jumper.

A trunk that has its terminations within a single facility.

Pertaining to software that will run on more than one operating system (i.e., on more than one platform).

The operation of two transmitters on the same frequency, but with polarizations in the opposite sense, e.g., plane polarization with one transmitter-receiver pair being vertically polarized and the other pair horizontally polarized.

In a satellite communications system, the signal power and control connections between the components of an Earth station.
Note: Examples of cross-site links are (a) links between transmitters and antennas and (b) links between control consoles and transmitters.

A switch that has a plurality of vertical paths, a plurality of horizontal paths, and electromagnetic means, i.e., relays, for interconnecting any one of the vertical paths to any one of the horizontal paths.

1. In audio programming, recording, or mixing, to combine signals in such a manner that one channel or source fades out as another fades in, while maintaining an essentially constant program volume.
2. The result produced thereby.

A data link between two satellites.

A single element that (a) is in the array of elements that compose a switch and (b) consists of a set of physical or logical contacts that operate together to extend the speech and signaling channels in a switched network.

1. Undesired coupling of a signal from one circuit, part of a circuit, or channel, to another.
2. Any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel.
Note 1: In telephony, crosstalk is usually distinguishable as speech or signaling tones.
Note 2: In video,… (Read More →)

The ratio of the power in a disturbing circuit to the induced power in the disturbed circuit observed at specified points of the circuits under specified terminal conditions.
Note: Crosstalk coupling is usually expressed in dB. Synonym crosstalk coupling loss.

Synonym crosstalk coupling.

Centralized Resources Over Wide Area Network

Cathode Ray Tube

1. Operations performed in converting encrypted messages to plain text without initial knowledge of the crypto-algorithm and/or key employed in the encryption. [INFOSEC-99]
2. The study of encrypted texts.
3. The analysis of a cryptographic system and/or its inputs and outputs to derive confidential variables and/or sensitive data including cleartext[7498-2].

Synonym (in cryptography) analytical attack.

[The] marking or designator identifying COMSEC keying material used to secure or authenticate telecommunications carrying classified or sensitive U. S. Government or U. S. Government-derived information. [INFOSEC-99]
Note: When written in all upper case letters, CRYPTO has the meaning stated above. When written in lower case as a prefix, crypto and crypt are abbreviations for cryptographic. [NIS]

Deprecated term. See key.

[A] circuit or device that detects failures or aberrations in the logic or operation of crypto-equipment. [A] crypto-alarm may inhibit transmission or may provide a visible and/or audible alarm. [INFOSEC-99]

[A] well-defined procedure or sequence of rules or steps, or a series of mathematical equations used to describe cryptographic processes such as encryption/decryption, key generation, authentication, signatures, etc. [INFOSEC-99]

Equipment designed specifically to facilitate efficient or reliable operation of crypto-equipment, without performing cryptographic functions itself. [INFOSEC-99]

Seecryptographic equipment.

[A] device or electronic key used to unlock the secure mode of crypto-equipment. [INFOSEC-99]

A complete system of crypto-communications between two or more holders. The basic unit for naval cryptographic communication. A cryptochannel is analogous to a radio circuit. It includes:
(a) The cryptographic aids prescribed.
(b) The holders thereof.
(c) The indicators or other means of identification.
(d) The area or areas in which effective.
(e)The special purpose, if any, for which provided.… (Read More →)

1. [The] art or science concerning the principles, means, and methods for rendering plain information unintelligible, and for restoring encrypted information to intelligible form. [INFOSEC-99]
2. The branch of cryptology that treats of the principles, means, and methods of designing and using cryptosystems.
3. The discipline which embodies principles, means, and the methods for the transformation of data in order… (Read More →)

Information which is derived by performing a cryptographic transformation (see cryptography) on a data unit [7498-2].
Note: The derivation of the check value may be performed in one or more steps and is a result of a mathematical function of the key and data unit. It is usually used to check the integrity of a data unit.

Hardware or firmware embodiment of the cryptographic logic. A cryptographic component may be a modular assembly, a printed wiring assembly, a microcircuit, or a combination of these items. [INFOSEC-99]

Any device that embodies cryptographic logic or performs one or more cryptographic functions (e.g., key generation, encryption, and authentication).

A mathematical function that maps values from a large (or even very large) domain into a smaller range, and is (a) one-way in that it is computationally infeasible to find any input which maps to any pre-specified output; and (b) collision-free in that it is computationally infeasible to find any two distinct inputs which map to the same output. [After… (Read More →)

Seecryptographic hash.

All information significantly descriptive of cryptographic techniques and processes or of cryptographic systems and equipment, or their functions and capabilities, and all cryptomaterial. [JP 1-02]

[A] function used to set the state of a cryptographic logic prior to key generation, encryption, or other operating mode. [INFOSEC-99]

A mathematical value that is used (a) in an algorithm to generate cipher text from plain text or vice versa, and (b) to determine the operation of a cryptographic function (e.g., the synchronized generation of keying material), or a digital signature computation or validation. [After X9.31]

The ability for two nodes, that have cryptographically processed a transaction, to determine the identical transaction key. [After X9.24]

The embodiment of one (or more) crypto-algorithm(s) along with alarms, checks, and other processes essential to effective and secure performance of the cryptographic process(es). [INFOSEC-99]

[A] function that randomly determines the transmit state of a cryptographic logic. [INFOSEC-99]

Seecryptographic key synchronization.

1. [The] art or science concerning the principles, means, and methods for rendering plain information unintelligible, and for restoring encrypted information to intelligible form. [INFOSEC-99]
2. The branch of cryptology that treats of the principles, means, and methods of designing and using cryptosystems.
3. The discipline which embodies principles, means, and the methods for the transformation of data in order… (Read More →)

Of or pertaining to cryptology. [JP 1-02]

1. The science that deals with hidden, disguised, or encrypted communications. It includes communications security and communications intelligence. [JP1-02]
2. [The] field encompassing both cryptography and cryptanalysis. [INFOSEC-99]

All material including documents, devices, equipment, and apparatus essential to the encryption, decryption, or authentication of telecommunications. When classified, it is designated CRYPTO and subject to special safeguards. [JP 1-02]

Stations holding a common key. [INFOSEC-99]
Note: Activities that hold key for other than use, such as cryptologistic depots, are not cryptonet members for that key. Controlling authorities are de facto members of the cryptonets they control. [NIS]

1. The time span during which a specific key is authorized or in which the keys for a given system remain in effect. [After X9.31]
2. [The] time span during which each key setting remains in effect. [INFOSEC-99]

See communications security.

[The] process by which a receiving decrypting cryptographic logic attains the same internal state as the transmitting encrypting logic. [INFOSEC-99]

Associated COMSEC items interacting to provide a single means of encryption or decryption. [INFOSEC]

An oscillator in which the frequency is controlled by a piezoelectric crystal.
Note 1: A crystal oscillator may require controlled temperature because its operating frequency is a function of temperature.
Note 2: Types of crystal oscillators include voltage-controlled crystal oscillators (VCXO), temperature-compensated crystal oscillators (TCXO), oven-controlled crystal oscillators (OCXO), temperature-compensated-voltage controlled crystal oscillators (TCVCXO), oven-controlled voltage-controlled crystal oscillators (OCVCXO), microcomputer-compensated… (Read More →)

1. Classification Scheme,
2. Circuit-Switched.

Call Session Control Function

Abbreviation for carrier sense multiple access.

Abbreviation for carrier sense multiple access with collision avoidance.

Abbreviation for carrier sense multiple access with collision detection.

1. Content Service Provider,
2. Communication Service Providers.

Content Service Provider Requirements

Abbreviation for channel service unit, circuit switching unit, customer service unit.

Previously known as the Cellular Telecommunications and Internet Association. As of 2018, referred to as CTIA -- The Wireless Association.

Common Technical Specifications

Abbreviation for Centrex® service.

The total transit delay applicable for a data call obtained by summing the individual transit delays of all component portions of the data connection. [T1.615-1992]

Common UNIX Printing System

The combined amount of changes billed, excluding arrears. [47 CFR Pt.36-A]

A movable, visible mark used to indicate a position of interest on a display surface.
Note: A cursor may have a controllable shape, such as an underline, a rectangle, or a pointer and usually indicates where the next character or graphic will be entered or revised.

Synonym macrobend loss.

Data compaction accomplished by substituting an analytical expression for the data to be stored or transmitted.
Note: Examples of curve-fitting compaction are (a) the breaking of a continuous curve into a series of straight line segments and specifying the slope, intercept, and range for each segment and (b) using a mathematical expression, such as a polynomial or a trigonometric function,… (Read More →)

One of an identified group of network-provided enhanced services.
Note: A CLASS group for a given network usually includes several enhanced service offerings, such as incoming-call identification, call trace, call blocking, automatic return of the most recent incoming call, call redial, and selective forwarding and programming to permit distinctive ringing for incoming calls.

1. The person or organization that purchases a Target of Evaluation [ITSEC].
2. The corroboration that the source of data received is as claimed.

In an Integrated Services Digital Network (ISDN), the portion of the ISDN access that a network provider supplies to connect the customer, i.e., subscriber, installation to the network.
Note: Customer access includes those network elements or portions of elements that extend from the access switch to the network interface.

Traffic which is both (a) handled to completion through pulses generated by the customer and (b) for which either a message unit charge, bulk charge or message toll charge is except for that traffic recorded by means of message registers. [47 CFR Pt.36-A]

All telecommunication equipment and wiring on the customer side of the network interface. [T
1. Rpt37-1994]

In network management, a complex that (a) is controlled by a customer and (b) is responsible for, and performs, maintenance for the customer installation.

1. Termination equipment that (a) is located on the customer premises and (b) performs a function that may be integrated into the common carrier equipment.
Note: An example of a customer office terminal is a stand-alone multiplexer located on the customer premises.
2. The digital loop carrier (DLC) multiplexing function that is near the exchange termination (ET) when provided by… (Read More →)

Deprecated term. See customer premises equipment.

1. Terminal and associated equipment and inside wiring located at a subscriber's premises and connected with a carrier's communication channel(s) at the demarcation point ("demarc").
Note 1: The demarc is a point established in a building or complex to separate customer equipment from telephone company equipment.
Note 2: Excluded from CPE are over-voltage protection equipment and pay telephones.
2. Items… (Read More →)

The segment of wiring from the customer's side of the protector to the customer premises equipment. [47 CFR Pt.36-A]

A device that provides an accessing arrangement at a user location to either switched or point-to-point, data-conditioned circuits at a specifically established data signaling rate.
Note: A CSU provides local loop equalization, transient protection, isolation, and central office loop-back testing capability.

Deprecated term. Seecustomer premises equipment.

In motion picture or television production or editing, an abrupt change from one scene to another.

A destructive technique for determining certain optical fiber transmission characteristics, such as attenuation and bandwidth, by (a) performing the desired measurements on a long length of the fiber under test, (b) cutting the fiber under test at a point near the launching end, (c) repeating the measurements on the short length of fiber, and (d) subtracting the results obtained on… (Read More →)

A waveguide, of adjustable length, which varies the attenuation of signals passing through it.

1. The frequency either above which or below which the output of a circuit, such as a line, amplifier, or filter, is reduced to a specified level.
2. The frequency below which a radio wave fails to penetrate a layer of the ionosphere at the incidence angle required for transmission between two specified points by reflection from the layer.

The highest order mode that will propagate in a given waveguide at a given frequency.

1. The wavelength corresponding to the cutoff frequency.
2. In an uncabled single-mode optical fiber, the wavelength greater than which a particular waveguide mode ceases to be a bound mode.
Note 1: The cutoff wavelength is usually taken to be the wavelength at which the normalized frequency is equal to
2. 40
5.
Note 2: The cabled cutoff wavelength is… (Read More →)

The physical changing of circuits or lines from one configuration to another.

Abbreviation for continuously variable slope delta modulation.

Control Word

Common Warehouse Metamodel

CPE WAN Management Protocol

Abbreviation for composite signaling.

Synonym composite signaling.

Abbreviation for carrier.

Loosely, a prefix referring to anything related to computers or networking.
Note 1: For example, a "cyber cafe" is a coffee shop that offers computer terminals for customers to browse the Internet while sipping coffee, and a "cybersleuth" is an investigator who researches and attempts to solve or find the cause of, unusual Internet occurrences.
Note 2: While "cyber" is… (Read More →)

See information security.

1. The aggregate of participants in the use of a portion of cyberspace.
2. A special-interest group (SIG) of cyberspace participants. Synonym wired community.

An electronic site shared by a number of commercial interests, and at which users can browse, shop, and place orders for the products listed at that site. [Bahorsky] Synonym Internet mall.

1. One who uses the Internet.
2. Synonym Web surfer.

The impression of space and community formed by computers, computer networks, and their users; the virtual "world" that Internet users inhabit when they are online.

The practice of registering Internet domain names--usually based on prominent trade names, trademarks, or corporate names--before the legitimate holders of same have had an opportunity or interest in registering the domain names for themselves.
Note: Cybersquatters engage(d) in this practice, which has now been ruled illegal, for the purpose of (a) denying the domain name(s) to, or (b) attempting to… (Read More →)

In telegraphy, distortion that (a) is periodic and (b) is not characteristic, not biased, and not fortuitous.
Note: Causes of cyclic distortion include irregularities in the duration of contact time of the brushes of a transmitter distributor and interference by disturbing alternating currents.

1. An error-detection scheme that (a) uses parity bits generated by polynomial encoding of digital signals, (b) appends those parity bits to the digital signal, and (c) uses decoding algorithms that detect errors in the received digital signal.
Note: Error correction, if required, may be accomplished through the use of an automatic repeat-request (ARQ) system.
2. [An] error checking mechanism… (Read More →)