c - Represents the speed of light in a vacuum, approximately 300,000 kilometers per second (186,000 miles per second).

C wire - A pair of 19 AWG [0.91 mm (0.036 in)] solid copper conductors in a polyethylene jacket; used for the extension of single telephone lines primarily in rural areas.

cabinet - A container that may enclose connection devices, terminations, apparatus, wiring, and equipment (TIA).

cable (CA) - An assembly of one or more insulated conductors or optical fibers within an enveloping sheath. (TIA)

cable assembly - A cable that has connectors installed on one or both ends. See also jumper and pigtail.

cable brake - See reel brake.

cable chase - A pathway used for telecommunications cable.

cable dip - Aerial cable that is transitioned down a utility pole and placed below grade distribution, typically occurring at the pole closest to the building. Also called a pole dip.

cable-end locator kit - Set of numbered 8-pin modular plugs that can be identified by the cable tester. Also called an office locator kit.

cable eye - See cable head.

cable fill - 1. The number of cables permitted in a pathway. Expressed as a percentage of the total cross-sectional area of the pathway. 2. The number of working pairs/optical fibers in a cable.

cable head - The end of the cable attached to the pulling device. Also called a cable eye.

cable modem - A device used to convert broadband signal from a community antenna television system to Ethernet used for high-speed Internet access.

cable rack - The vertical or horizontal open support structure (usually made of aluminum or steel) that is attached to a ceiling or wall.

cable reel brake - See reel brake.

cable reel - A spool or bobbin for storing and distributing cable.

cable run - A length of installed media, which may include other components along its path. (TIA)

cable sheath - A covering over the optical fiber or copper conductor assembly that may include one or more metallic members, strength members, orjackets. (TIA)

cable support system - A combination of conduits, cable trays, open top support hooks (j-hooks), tie wraps, and other hardware pieces used in a cabling installation to support cables. Cable support systems limit cable stress and may provide some mechanical protection to the cables being supported.

cable terminal - An assembly used to access the conductors of a cable.

cable termination - The connecting or termination hardware applied to the end of a cable for the purpose of facilitating connection to active or passive transmission equipment.

cable termination hardware - Obsolete term. Refer to connecting hardware.

cable throw - A changing of the circuit identity of cable pairs by splicing to pairs of a different identity.

cable tray (CT) - A rigid structure for housing and protecting cables or conductors. Usually consists of one-piece solid or ventilated bottom or individual transverse members with two side rails.

cable tree - A vertical rack with multiple arms for holding reels of cable.

cable trough - A raceway consisting of metal trough and fittings, formed and constructed so that insulated conductors and cables may be readily installed or removed without injury either to conductors or their coverings.

cabling - A system of cables, cords, and connecting hardware.

cabling system - A specific system of cables, equipment/patch cords, connecting hardware, and other components supplied as a single entity.

caching - A technique that provides faster access to data by storing a copy of recently used or likely to be used data to fast, accessible memory. For example, selected data on a computer hard drive could be stored in the computer's random access memory for faster access.

calibration - Task of verifying test equipment against a reference.

campus - The buildings and grounds having legal contiguous interconnection. (TIA)

campus area network (CAN) - A telecommunications system that links LANs located in two or more buildings in close proximity to each other.

campus backbone cabling - A cable that connects the main cross-connect (campus distributor) to the intermediate cross-connect(s) (building distributor[s]). Campus backbone cables also may connect intermediate cross-connects (building distributors) directly.

campus distributor (CD) - The distributor from which the campus backbone cabling emanates. (ISO, CENELEC, AS/NZS) International equivalent term for main cross-connect.

CAP-16 Carrierless amplitude/phase modulation with 16 distinct signals. - CAP-16 is used to encode 155 Mbis asynchronous transfer mode (ATM) into a signal with a bandwidth of 25.8 MHz. CAP-16 is also used to encode 51 MbIsATM into a signal that can be supported by a category 3 cable.

CAP-64 Carrierless amplitude/phase modulation with 64 distinct signals - CAP-64 is used to encode 622 Mbls asynchronous transfer mode into a signal with,a bandwidth of 25.8 MHz.

capacitance (C) - 1. The ability of an electronic component to store electrical energy. 2. Opposition to a change in voltage.

capacitance unbalance - A capacitance unbalance between conductors of two pairs (or between the conductors and the ground) that are located in close proximity to each other within a cable that can result in the undesirable transferring of signal that is commonly referred to as crosstalk.

capping - 1. Applying a closure device to an insert after the floor fitting is removed. 2. Covering cables located within a wall chase. 3. Sealing the end of a cable to prevent moisture intrusion prior to termination.

capstan - A device for pulling cable.

carbon block - See carbon protector.

carbon protector - An overvoltage protector that uses closely spaced carbon electrodes (granules) for voltage limiting.

card access - An access control system using encoded cards and card readers to identify card readers and determine whether access may be granted.

card encoder - A device used to encode data onto an access card.

cardholder - An individual who has been assigned an access control card.

carding brush - See wire brush

card reader - A device that retrieves information stored on an access card or badge and transmits the information to a controller. Also called badge reader.

carrier - A signal modulated by an information source, thereby making it carry the information. See also access provider (AP).

carrierband - A hybrid of baseband and broadband signaling. Signals may be transmitted from either digital or analog sources. Baseband signals are digital (digital source domains) requiring all of the available bandwidth in a single, shared connection. Broadband signals are analog (having either analog or digital sources) and move over unshared channels on a shared connection.

carrier sense multiple access with collision avoidance (CSMAICA) - A media access control protocol utilized by wireless LANs. Network devices "listen" to the network by sending a broadcast signal before real data is sent.

carrier sense multiple access with collision detection (CSMAICD) - A media access control protocol originally developed for use on wired Ethemet networks. Defines how network devices respond when multiple devices simultaneously attempt to send data over the same channel.

carrier sensing - The monitoring of a communications channel to check if it is free before transmitting (i.e., to see if any network devices are transmitting).

carrier-to-interference ratio (C/1) - The ratio between the desired carrier signal at the receiver end and the strongest cochannel carrier signal, expressed in dB.

category - A rating that defines the performance of cabling components and systems. Describes mechanical properties and transmission characteristics of balanced twisted-pair cabling and provides a numbered designation. Categories are defined in many regional standards (e.g., ANSI/TIA/EIA, ISO, ASINZS, JIS).

category 3 - Balanced twisted-pair copper cable specifications characterized in a frequency range of 1 to 16 MHz.

category 4 - The Telecommunications Industry Association no longer recognizes this category.

category 5 - The Telecommunications Industry Association no longer recognizes this category. ISOIIEC 11801.E.0.2, Generic Cabling for Customer Premises, does recognize this category. It is the functional equivalent of TIA category 5e.

category 5e - Balanced twisted-pair copper cable specifications characterized in a frequency range from 1 to 100 MHz. This category specified transmission parameters that were not characterized by category 5 (e.g., power sum near-end crosstalk, return loss, equal level far-end crosstalk, power sum equal level far-end crosstalk) and features more stringent near-end crosstalk than category 5.

category 6 - augmented Balanced twisted-pair copper cable specifications characterized in a frequency range from 1 to 500 MHz. The augmentation from ca-tegory 6 covers frequency range, insertion loss specifications, and alien crosstalk mitigation.

category 7 - Balanced shielded twisted-pair copper cable specifications characterized in a frequency range from 1 to 600 MHz.

catenary wire - See support strand (messenger).

cathodic protection - A system used to provide a constant low-current flow in equal and opposite polarity to the existing electrolysis current flow.

catwalk - Elevated walkway provided in some buildings to help workers reach utilities.

cavity wall - A wall built of solid masonry units arranged to provide air space within the wall. (TIA)

cdma2000 - An air interface, developed under third generation partnership project two that evolved from second-generation mobile telephony code division multiple access interim standard-95.

ceiling distribution system - 1. A distribution system that utilizes the space between a suspended or false ceiling and the structural surface above. (TIA) 2. In open-ceiling areas, cables serving the work area outlets from above.

cell - 1. A single raceway of a cellular or underfloor duct system. (TIA) 2. A 53-byte data transfer unit used by asynchronous transfer mode networks. 3. The fixed area in which a wireless base station is configured to operate. See also zone. 4. A single wireless LAN access point and its associated clients.

cell sectorization - A method of increasing cellular radio capacity by changing the horizontal beaming pattern of the cell. Sectorization breaks an existing cell into two 180 degree wedges or three 120 degree wedges.

cell splitting - A method of increasing cellular radio capacity by reducing the diameter of the original cell then adding additional cells to cover the same area. Cell splitting can be performed on a single cell or sectorized cells. See also sectorized cells.

cellular digital packet data (CDPD) - A contention-based packet access scheme for analog cellular channels. CDPD transmits and receives digital data on idle analog cellular channels at 19.2 kb/s.

cellular floor (CF) - A floor distribution method in which cables pass through floor cells, constructed of steel or concrete to provide a ready-made raceway for distribution of power and telecommunications cables. (TIA)

cellular floor raceway - An assembly of hollow, longitudinal units constituting part of a floor, and systematically placed for the distribution of cables. (TIA)

CE marking - A Conformite Europeene mark fixed to the product itself or its packaging, instructions for use, or guarantee certificate. It indicates that the product complies with all relevant European directives that call for its application (e.g., electromagnetic compatibility directive).

cementitious firestop - A firestopping material that is mixed with water, similar in appearance to mortar. See also firestopping. (TIA)

center channel - Third front audio channel (in addition to main stereo left and right channels) found in surround sound audio systems with the primary task of reproducing movie dialogue (what the actors are saying) thus locking the voices to the screen for all listeners.

centralized cabling - An optical fiber cabling configuration from the work area to a centralized cross-connect using pullthrough cables, an interconnect, or splice in the telecommunications room.

central member - The center component of a cable installed as a strength element.

central office (CO) - A common carrier switching center office (also called central office or public exchange) that is conveniently located in areas to serve subscriber homes and businesses.

central processing unit (CPU) - That part of a computer in which logical operations are performed.

centricity - The center-to-center distance between paired copper conductors.

certification test set - A test set designed specifically to measure the properties of a circuit to determine whether the circuit meets standards.

change management - A term used to describe the process of tracking all network modifications.

change order - A document issued after the construction agreement has been signed authorizing modifications of the work to be completed or an adjustment in the contract sum or time. (CSI)

channel - 1. The end-to-end transmission path connecting interfaces of any two pieces of application-specific equipment. Equipment cords and work area cords are included in the channel. 2. In frequency division multiplexing, a band in the frequency spectrum that is assigned to a specific logical connection. 3. In time division multiplexing, a time that is assigned to a specific logical connection.

channel bank - A multiplexing device that divides a high-speed digital service into multiple, smaller, fixed-size channels that can be separately accessed. The device also allows several channels to be linked into larger bundles (often referred to as Nx64).

channel service unit (CSU) - A customer premises device that connects the data terminal equipment to a digital line from the public network service provider.

channel stock - A metallic U-shaped bar with or without evenly spaced holes. Often hung in a trapeze configuration for support of pathway systems, such as conduits and cable trays.

characteristic impedance - The input impedance of a circuit or a uniform transmission line with a constant voltage to current ratio at any point along the line.

chase nipple - A metallic bushing used with a locknut, inserted into a hole (typically in a metal enclosure) to protect cabling from abrasion on sharp edges.

chat - A basic text display application that allows two or more users to communicate in real-time over a network. A text message typed by any user is instantly displayed on the screens of all users.

checksum - A value calculated from the binary content of a message. It is used by the receiving device to verify that the data has not been altered during its transfer from source to receiver. See also frame check sequence. chemical grounding electrode Copper tubes containing a chemical that slowly leaches into the soil, lowering the soil's resistance. Also called a chemical ground rod.

chip rate - The rate at which the chipping sequence used in direct sequence spread spectrum modulation changes.

chipping sequence - The spreading code used in direct sequence spread spectrum modulation. Each value in the spreading code is called a chip.

chromatic dispersion - A result of the phenomenon that the velocity of propagation in a medium is frequency dependent, which causes the frequency components of a pulse to lose phase coherence as it propagates (e.g., a transmitted pulse will spread out as it propagates).

churn - The rate that customers move from one service provider or system to another.

cipher lock - A mechanical combination lock that is used in access control to unlock a knob or level or to actuate a set of contacts.

circuit (ckt [U.S.], cct [European]) - The electrical or optical path used for communications between two devices.

circuit gateway - A firewall that permits anbound or outbound connection to take place on the basis of authentication and authorization criteria. This type of firewall does not inspect each datagram-once the device is granted access to the communications channel, it can send and receive any type of message.

circuit switching - A communications method in which a dedicated communications path is established between two devices prior to message transfer. Contrast with packet switching.

circular mil - Measuring unit used to specify the cross-sectional area of conductors.

circulators - See isolators

cladding - The outer concentric glass layer that surrounds the optical fiber core and has a lower index of refraction than the core,

class - A set of performance specifications, separated into six classes, A-F, for balanced cabling. This allows the successful transmission of applications over channels according to defined annexes in ISO 11801, which lists the applications and the minimum performance class required.

class A - The International Organization for Stan dardization/Intemational Electrotechnical Commission balanced twisted copper cabling specifications characterized in a frequency range up to 100 kHz.

class B - The International Organization for Standard izationllnternational Electrotechnical Commission balanced twisted copper cabling specifications characterized in a frequency range up to 1 MHz.

class C - The International Organization for Standardization/International Electrotechnical Commission balanced twisted copper cabling specifications characterized in a frequency range up to 16 MHz.

class C fire extinguisher - Fire extinguisher that does not have any chemicals with conductive properties so it can be used for electrical fires.

class D - The International Organization for Standardization/International Electrotechnical Commission balanced twisted copper cabling specifications characterized in a frequency range up to 100 MHz.

class E - The International Organization for Standard ization/lnternational Electrotechnical Commission balanced twisted copper cabling specifications characterized in a frequency range up to 250 MHz.

class F - The International Organization for Standardization/International Electrotechnical Commission balanced twisted copper cabling specifications characterized in a frequency range up to 600 MHz.

clear to send (CTS) - A frame type used as a reply to the request to send component when the wireless medium is available for transmission

cleave - The process of breaking an optical fiber by a controlled fracture of the glass.

cleaver - A device that properly cuts the ends of optical fibers.

client software - Additions to a station's operating system that enable access to network resources.

client/server model - A form of distributed computing in which a series of interdependent tasks are processed by two or more computers on a network, allowing client devices with limited processing capabilities to gain access to the available resources of one or more servers attached to the network.

clock - A signal used to synchronize communications between devices.

closed loop secure - A closed or continuous circuit or monitoring loop when a door or monitoring equipment is secure.

closed-circuit television (CCTV) - A private television system, typically used for security purposes, in which the signal is transmitted to a limited number of receivers.

clove hitch - A knot consisting of two half hitches made in opposite directions, forming a nonslip loop

cluster - A collection of servers and associated storage devices interconnected using a dedicated, high-speed network. The collection appears as a single device to the network. All incoming requests are divided among the servers for quicker response. See also load balancing.

clustered star - Similar to a tree topology, except that there are clusters of devices at the end of each branch. Also called a bus star topology.

coating - See buffer coating.

coaxial cable - A cable consisting of a central metallic inner conductor separated from an enclosing outer conductor by a dielectric material. This material may be solid, foam, a suitable gas, or dry air. The outer conductor comprises a metallic braid, a foil layer, combination of braid and foil.

co-channel - Any condition in which two or more users share a single channel. (Nortel)

code - A rule intended to ensure safety during the installation and use of materials, components, fixtures, systems, premises, and related subjects. Codes are typically invoked and enforced through government regulation.

codec - A device that can transform an analog signal into a digital bit stream (coder) and digital bit stream into an analog signal (decoder).

coderldecoder - See codec.

coefficient of expansion - A formula to determine the physical expansion or contraction of a material due to temperature change (e.g., conduit, cable).

collapsed backbone - An internetwork contained in one device. Individual networks are connected to this central device and can then communicate with one another.

collapsed backbone cable - An optical fiber cable, in a synchronous optical network (SONET), which serves a building off of the SONET fiber ring without redundancy.

collision - An event on a network indicating that two or more devices have simultaneously accessed the communications channel.

collision avoidance - A network contention protocol that requires devices to actively monitor a network for traffic before sending information.

collision detection - The process initiated when two or more network devices on an Ethemet network attempt to send a message at the same time and their messages collide. A device stops transmitting when it detects a collision and only attempts to retransmit after waiting a random period of time.

collision domain - A collection of network devices and segments connected by repeaters. When a device in a collision domain transmits a Data Link layer frame, all other devices in the same domain receive the transmission. Devices and segments separated by bridges, routers, or switches are said to be in different collision domains.

colocation - Building or floor space occupied by multiple users sharing the facilities and services of the building or floor to house their equipment (e.g., Internet data center).

comma-separated value (CSV) - A file format where each line represents one entry or record and the fields in a record are separated by commas.

commercial building - A building, or portion thereof, that is intended for office use. (TIA)

committed information rate (CIR) - A value that specifies the minimum data rate guaranteed to the applicable subscriber.

common carrier - See access provider (AP) and service provider (SP).

common intermediate formatlstandard input format (CIFISIF) - An International Telecommunication Union standard for the size of a video image on a computer screen, defined at 352 x 240 pixels. See quarter common intermediate format/quarter standard input format.

common-mode (CM) circuit - The closed circuit for the common-mode or ground loop current.

common-mode (CM) noise (and longitudinal) - See common-mode voltage and longitudinal noise.

common-mode (CM) voltage - A symmetrical noise voltage that is coupled into a cabling channel or link with equal magnitudes and in phase from each conductor measured at the cable's point relative to ground potential.

communications - See telecommunications.

communications plenum (CMP) cable - Type CMP shall be listed as being suitable for use in ducts, plenums, and other spaces used for environmental air and shall also be listed as having adequate fire-resistant and low smoke-producing characteristics.

communications protocol - See protocol.

communications riser (CMR) cable - Type CMR communications riser cable shall be listed as being suitable for use in a vertical run in a shaft or from floor to floor and shall also be listed as having fireresistant characteristics capable of preventing the carrying of fire from floor to floor. (NEC)

community antenna television (CATV) system - A system of television reception in which signals from distant stations are picked up by a master antenna and sent by cable to the individual receivers.

compander - A device that can reduce (compress) the dynamic range of the signal (e.g., prior to transmission) and recover (expand) the dynamic range (e.g., after transmission).

companding - A process in which a dynamic range of a signal is reduced and then expanded to its original range.

compartmentation - The segregation of components, programs, and information. Provides isolation and protection from compromise, contamination, or unauthorized access.

complementary code keying (CCK) - A single carrier modulation technique used in IEEE 802.11b and IEEE 802.11g networks.

completion bond - An obligation made binding by a money forfeit that ensures a contractor will finish a project to the specifications of its request for quote within a specified time.

composite cable - Made up of multiple dissimilar cables within one jacket. See also hybrid cable.

compound curve - curves, each with a different radius, all turning in the same direction. A series of two or more

compression - The coding or modification of data from its original form in order to save storage space or transmission time.

compressorldecompressor - See codec. Also called a compander compressor/ expander.

compressor/expander - See compander.

concentrator - A device that combines data from several active inputs into one shared channel that can be separated after transmission. The concentrator's output bandwidth must be greater than the total bandwidth of all simultaneously active inputs.

concrete fill - A minimal-depth concrete pour to encase single-level underfloor duct. (TIA)

concrete universal enclosure (CUE) - environmentally enclosed Aboveground cabinets.

concrete-encased electrode - An electrode encased in concrete that is in direct contact with the earth.

conductance (G) - The measure of the ease with which electrical current flows through a conductor. Uniformly distributed along the conductor length, conductance varies as a function of a conductor's geometry and the dielectric properties of the materials surrounding the conductor. One of the primary transmission parameters for transmission lines is the opposite of resistance. The unit of measure is siemens (S).

conductor - A media (i.e., solid, liquid, gas) for transmitting electric current, electromagnetic waves/light.

conduit - 1. A raceway of circular crosssection. 2. A structure containing one or more ducts. (TIA)conduit body A conduit coupling that has a removable cover to allow access to the cable for pulling purposes. Also called an LB.

conduit elbow - A bend in a section of conduit, usually at a specified radius and degree of turn.

conduit run - Multiple sections of conduit that are joined together with fittings.

conduit shoe - A device placed at the open end of a conduit to assist in bending a cable that extends out of the conduit.

conduit stub-out - A short section of conduit that is installed from a receptacle box, usually in a wall, curved into an accessible ceiling space.

conduit stub-up - A short section of conduit that is installed from a receptacle box, usually in a wall, into an accessible ceiling space directly above the receptacle box.

conduit system - Any combination of ducts, conduits, maintenance holes, handholes, and vaults joined to form an integrated whole. (TIA)

cone - Safety marker that is used to designate a secure off-limits area for nonworkers.

cone of protection - A cone-shaped space, the apex of which is the top of the conductor or lightning protective mast and with the base being a circle at the earth surface. See zone of protection.

conferencing - The process of communicating among users over a network in real-time, using any combination of text, voice, and video.

confidentiality attack - Another term for data theft.

configuration and name management - The identification, implementation, modification, and tracking of the settings necessary for a given device to operate in the intended manner.

confined space - The work space defined by the Occupational Safety and Health Administration as one a worker can enter and work in but that has limited or restrictive means of entry or exit and that is not designed for continuous occupancy (e.g., maintenance holes, splice pits, crawl spaces, attics).

congestion - A state in which the volume of messages exceeds the designed capacity of a communications channel or network fabric, resulting in transfer delays or failures.

connecting hardware - A device, or a combination of devices, used to connect cables or cable elements.

connectionless communications - No logical communications path is established between a sending device and a receiving device prior to data transfer. Each data unit may be delivered over a different path.

connection-oriented communications - A logical communications path is established between a sending and a receiving device prior to data transfer. Each data unit is delivered over this preestablished path.

connector - A mechanical device used to provide a means for aligning, attaching, and achieving continuity between conductors or optical fibers.

connector insertion loss - Attenuation associated with the physical attachment of two connectors

connector keying - The physical feature of a connector system that guarantees correct orientation of the connector.

connector, duplex; optical fiber - A remateable device that terminates two optical fibers and mates with a duplex receptacle. (TIA)

connector, small form factor - An optical fiber duplex connector with a footprint approximating that of an 8-position outlet connector typically used with 4-pair copper connectors.

connectorization - To attach to or fasten together by means of connectors and splices telecommunications circuits. Applies to optical fiber, balanced twistedpair, and coaxial cable.

consistency check - A method of verifying the confidence of a field measurement.

consolidation point (CP) - A location for interconnection between horizontal cables extending from building pathways and horizontal cables extending into furniture pathways. (TIA)

construction document (CD) - The written and graphic document prepared or assembled by the architect or engineer for communicating the design of the project.

construction management and manager - An added participant in the process, employed by the owner to oversee and administer the project.

consultant - A specialist who provides services to the design team that is headed up by an architect or engineer who is under contract with the owner.

contact - A conducting circuit that makes or breaks a circuit.

contact rating - The specifications or load rating of a switch. Ratings are at "maximum voltage" or "current."

containment - 1. The process of dividing a structure into fire zones. Also called compartmentation. 2. A term used in the United Kingdom to describe cable raceway products (e.g., wall trunking, basket trunking, galvanised tray work).

content acceleration - The process of loading data accessed frequently by a large number of users onto devices capable of transferring the data more rapidly than the existing servers can transfer.

content access - The process of providing remote users the means to connect to a LAN to obtain specific information. See resource access and transactional access.

content filtering - The process of restricting the entry or exit of unauthorized or unwanted data (e.g., e-mail attachments) to and from a network.

contention - A network access method in which devices compete for use of the available communications channel.

contention domain - See collision domain

contingency - A sum of money, usually a percentage of the estimated construction cost, held in reserve to pay for unforeseen costs that may arise during a project

continuity test - A test that validates whether a material can conduct current or light.

continuous duty - A device that can operate continuously with no off or rest periods.

contract documents - Plans, specifications, and other documents that together set forth the requirements of the contract and become legally enforceable when the agreement is signed. Executed agreements between owner and contractor that become part of the contract when the agreement is signed. (CSI)

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

controlled access unit (CAU) - controlled access unit (CAU)

controlled environment - An outside plantrated enclosure with humidity, temperature, flood, and wind controls to provide protected conditions for sensitive electronic equipment.

controlled environment vault (CEV) - An environmentally controlled underground enclosure used to house equipment and termination points.

controller - A microprocessor based circuit board that manages access to a secure area. The controller receives information that it uses to determine through which doors and at what time cardholders are granted access to secure areas. Based on that information, the controller locks/ unlocks doors, sounds alarms, and communicates its status to a host computer.

control mode - A form of remote access where a network administrator uses the remote station to monitor or modify a specific LAN device or general network operations. A specialized form of terminal services also called a remote control. Contrast with browser mode, terminal mode, and transparent mode.

control module (CM) - A unit that provides addressable outputs for signaling devices (e.g., fire alarm horns, speakers).

control panel - A device that provides for the operational control of an automated system.

convergence -The linking of many systems, which remain independent in operation, to common information transport systems. As related to electronic safety and security, convergence involves many si-milar and dissimilar systems and facilitates their integration. See also integration.

converter - 1. A device that changes a signal from one transmission medium type to another (e.g., from copper to optical fiber). 2. A device that changes from one signaling type to another (e.g., analog to digital). coordinated protection The application of protection engineering across a set of premises systems to prevent electrical failure of telecommunications cabling and equipment.

copper distributed data interface (CDDI) - The twisted-pair cabling implementation for optical fiber.

core - The central, light-carrying part of an optical fiber through which light pulses are transmitted.

core area - See building core. (TIA)

core hitch - The weaving of copper conductors or pairs through a pulling eye for the purpose of pulling the cable.

core wall - Building structure that runs from the structural floor to the structural ceiling to separate the core area from the rest of the building.

corner frequency - In shielded cabling, the frequency at which the skin-effect depth is equal to the thickness of the shield.

corrosion area - A space that is subject to a high degree or risk of deterioration to elements.

coupled bonding conductor (CBC) - A bonding conductor placed (e.g., strapped) on the outside surface of telecommunications cable; used to reduce transient noise.

coupler - A device for connecting two other devices (e.g., connectoriied cables) together.

Coupling - The electromagnetic energy transfer from a disturbing circuit.or channel into a disturbed circuit or channel due to either separated or combined influence of electric and magnetic fields.

coupling attenuation - The relation between the transmitted power through the conductors and the maximum radiated peak power, conducted and generated by the excited common mode currents. (ISO)

coverage area - A building space where building automation system devices interact with the related system's equipment. Counterpart of the telecommunications work area.

coverage density - The number of stations in a wireless network coverage zone.

crawl space - Limited access building space that may be used for the placement of cabling.

crimp - The act of clamping connectors to a conductor or cable.

crimp head - A section of a splicing rig that fits over an assembled modular connector on the splicing head to provide the crimping of the module.

crossbar - An electromechanical switching system

crossbrace - A transverse brace that may be used as a support mechanism for the walls of a trench used in outside plant cabling pathways.

cross-connect - A facility enabling the termination of cable elements and their interconnection or cross-connection. (TIA)

cross-connection - A connection scheme between cabling runs, subsystems, and equipment using patch cords or jumpers that attach to connecting hardware on each end. (TIA)

cross-coupling - The coupling of a signal from one circuit or conductor to another.

crossed pairs - An error condition where physical connection of a wire or wires in a pair of wires is made to another wire or wires in yet another pair of wires generally found in the same cable.

crossover - The junction unit at the point of intersection of two cable trays, raceways, or conduit (pathways) on different planes. (TIA)

crossover cable - A cable for reversing transmit and receive at each end used to enable two network devices to communicate between each other.

cross-polar discrimination (XPD) - The difference in antenna gain or device response between a signal arriving on one polarization and one arriving on the opposite polarization (expressed in dB).

crosstalk - Unwanted transfer of signal from one or more circuits to other circuits as a result of electromagnetic interference.

cross threading - When the thread pattern of a nut and bolt do not match, a stripping (cross threading) of the thread pattern can occur during installation.

cryptographic security device - A hardware attachment that must be connected to a device before access can be granted. It can be used in conjunction with a password to authenticate a user. See also authentication.

cryptography - The field of study associated with encryption.

curing - A chemical process expected over time.

current (1) - Flow of electrons in a conductor measured in amperes.

customer-owned pole - An outside plant pole owned solely by the customer.

customer premises - Building(s), grounds, and appurtenances (belongings) under the control of the customer. (TIA)

customer premises equipment (CPE) - Telecommunications equipment located on the customer's premises. (TIA)cut An excavation or the removal of earth.

cutover - The process of switching from old network components to new network components. Used when describing the switch of a piece of equipment {e.g., a computer terminal, telephone} from an existing channel to a newly installed channel. See flash cut and hot cut.

cutsheet - 1. A listing of cable pair assignments used to specify desired circuit connections in a splice or cross-connect. This listing can also serve as the as-built of a splice or cross-connect field. 2. Cable documentation that shows the existing cable plant, the new cable plant, and the cross-connects that will be relocated during cutover. 3. Defines product specifications that may include drawings.

cut-through - A switching method in which messages are forwarded as they are received, with no error checking. See also modified cut-through and store-andforward.

cyclic redundancy check (CRC) - An error detection technique based on a mathematical calculation that adds bits to a transmitted data stream for the purpose of error detection at the receiver.