A--The Global System for Mobile Communications interface between the basic service set and network substation.

A3 - A stream cipher used for authentication in the Global System for Mobile Communications authentication center database subsystem.

A5 - A stream cipher used for encryption of transmissions in the Global System for Mobile Communications authentication center database subsystem.

A-bis - The Global System for Mobile Communications interface used when the base station controller is not collocated with the base transceiver station.

ablative - The development of a hard char that resists the erosion of fire and flames; a characteristic of a firestop when exposed to fire.

above finished floor (AFF) - Standard mounting height or vertical distance (e.g., 48 inch AFF) for a fixture, ceiling, device or any other object measured from the finished floor surface to the center line of the object as the measurement point.

absorption 1. A phenomenon causing attenuation of a radio signal passing through a medium. It occurs when gaseous molecules or suspended water particles in the atmosphere absorb the signal energy and convert it into heat due to molecular resonance. 2. In the transmission of electrical, electromagnetic, or acoustic signals, the conversion of the transmitted energy into another form, usually thermal. Absorption is one cause of signal attenuation.

accelerator - A chemical agent used to hasten a chemical reaction for setting permanent bonds on epoxy glues.

acceptance angle The half-angle of the cone within which incident light is totally internally reflected by the optical fiber core/cladding boundary. The light within this cone is coupled into reflected modes of the optical fiber.

acceptance plan - A facilitating agreement between parties (e.g., contractor and client or client representative) that defines satisfactory completion of a project task or complete project. It may include items on which the client's acceptance is dependent (e.g., delivery of as-built drawings, test certification).

acceptance test - A test or set of tests performed to demonstrate satisfactory completion of a predetermined task or group of tasks on which acceptance is dependent.

access - The process of connecting to a network.

access code - The numeric or alphanumeric characters that, when -entered correctly, authorize access into a secure area.

access control (AC) 1. The manner in which devices are granted or denied access to the resource in cases where two or more devices simultaneously attempt to use a shared resource (e.g., telecommunications circuit between two sites, specific printer). 2. An identification device assigned to an individual to give that individual access rights to an access control system.

access control (AC) card - An identification card with encoded information that, when presented to a card reader, identifies the cardholder to the access control system, allowing that system to determine the cardholder's entrance and exit rights.

access controller - A component of an electronic access control system whose primary function is to consolidate field-mounted peripheral devices and communicate bidirectionally between the system's headend software and fieldmounted peripheral devices.

access control list (ACL) - The database that keeps track of and controls access to network services or physical entry to an area through assigned privileges for users and groups. Also called authorization profile.

access control mechanism - The way devices on a LAN are granted or denied access to the network.

access control system - An interconnected set of controllers, managing the entrance and exit of people through secure areas.

access floor - A system consisting of completely removable and interchangeable floor panels that are supported on adjustable pedestals or stringers (or both) to allow entry to the area beneath.

access group - A superset of information, including time zones and secured doors, that is applied toward holders. This information defines at what time of day and through which doors cardholders are granted access.

access level matrix An access control system reference that is specific to each system for which it is being utilized. The purpose of the document is to provide a hierarchy of rights and privileges for different user groups and their associated authorized zones.

access line - A telecommunications circuit provided by a service provider at the demarcation point.

access parameter - The programmed information that defines the conditions that must be met to grant access to a secure area.

access point (AP) 1. The point of entry into a secure area. 2. A stand-alone hardware device or a computer wireless adaptor with software that acts as a wireless communication hub for users of wireless devices to connect with each other and to bridge those devices to the cabled portion of the network.

access protocol - The set of procedures that enables a user to obtain services from a network (e.g., carrier sense multiple access with collision detection and token passing for LANs). Also called media access control protocol.

access provider (AP) 1. A company (e.g., telephone company) that provides a circuit path between a service provider (SP) and the client user. An AP also can be the SP. 2. The operator of any facility that is used to convey telecommunications signals to and from a customer premises. See also service provider (SP).

accounting - Tracking of all authentication requests and resource access attempts (successful or failed) for review by network administrators and auditors.

accounting management - The tracking, billing, and cost allocation for network resource use.

acknowledgment (ACK) - A frame used in IEEE 802.11 to acknowledge that an error-free, data-free, frame has been received.

acoustical coupling Describes how acoustical vibrations in one media resonate into another media without a direct connection.

acrylate A coating applied during the optical fiber manufacturing process to provide physical and environmental protection for the optical fiber.

active card A type of access card that is dependent upon a card reader to provide the power necessary to allow the card to transmit its data.

active circuit Any circuit connected to an energized system.

active cross-connect A facility enabling the termination of cable elements and their interconnection or cross-connection by electronic means.

active equipment Energized equipment used for receiving or transmitting analog or digital signals (e.g., switches, hubs, routers, private branch exchanges).

active hub A powered device that can amplify, retime, or regenerate incoming signals to minimize errors and message corruption. See also hub and passive hub.

active monitor A device that monitors the operation of the ring on a token ring LAN.

active tracking A method of compensation for alignment variations in antennas.

adapter A device that enables any or all of the following: o Different sizes or types of plugs to mate with one another or to fit into a telecommunications outlet, o The rearrangement of leads, o Large cables with numerous conductors to fan out into smaller groups of conductors, and o Interconnection between cables. (TIA)

adapter - optical fiber duplex A mechanical device designed to align and join two duplex optical fiber connectors (plugs) to form an optical duplex connection. (TIA)

addendum A document used to provide additional requirements and recommendations to a published document (e.g., standards, contracts). When published, an addendum effectively becomes part of the document that it supports.

address 1. A unique identification code assigned to a network device, used to associate a message with its source and destination. See device address, medium access control (MAC) address, and network address. 2. A unique location in a computer's memory or other electronic storage medium. See medium access control (MAC) address and network address.

address resolution - A process used to associate network addresses with media access control addresses.

ad hoc network A peer-to-peer network characterized by communication between nodes without the need for an infrastructure. Also called independent basic service set.

adjacent channel discrimination A measure of the ability of a receiver to successfully receive a signal in a wanted frequency channel in the presence of unwanted signals on adjacent frequency channels, which are being picked up by the antenna.

adjacent channel interference Interference caused by the residual energy of a neighboring radio frequency channel overlapping onto the desired channel.

adjacent channel rejection The ability of a receiver to reject interference caused by a transmitter operating on an adjacent channel.

administration 1. The methodology defining the documentation requirements of a cabling system and its containment, the labeling of functional elements, and the process by which moves, additions, and changes are recorded. (ISO) See also labeling system. 2. See network administration.

advanced encryption standard (AES) A National Institute of Standards and Technology secret key encryption using 128 to 256 bit keys.

aerial-buried plant A general term for all outside plant cable runs made up of both aerial and direct-buried cables. aerial cable Telecommunications cable installed on aerial supporting structures (e.g., poles, sides of buildings, other structures). (TIA)

aerial entrance An entrance facility where the cables providing service to a building are placed overhead and the entry point is located above the ground level.

aerial plant An overhead infrastructure to provide telecommunications services between facilities.

afterset insert See insert, afterset.

agent An application to collect information about a device and make that information available to a network management system. Agents operate in managed devices on the network (e.g., hubs, switches, servers, stations).

air bottle Portable compressed air or gas source.

air feeder pipe An underground pipe that parallels cable runs and is used to supply air for pressurized cables.

air handling unit (AHU) Monitors and controls the air by volume, temperature, and humidity before being released into a specified building area. Typically, an AHU consists of a fan, hot and/or cold coils, and supply/return ducts and dampers. The AHU mixes indoor/outdoor air and passes the mixture of air through the coils.

air terminal A strike termination device that is a point receptor for attachment of flashes to the lightning protection system and is listed for the purpose. Typical air terminals are formed of a tube or solid rod. Also called a lightning rod.

alarm indicator A device or a combination of devices (e.g., bell, lamp, strobe, horn, gong, buzzer) that responds to a signal from an alarm sensor and indicates a fault or emergency condition.

alien crosstalk A measure of the unwanted signal coupling between adjacent cabling or components.

alien far-end crosstalk (AFEXT) A measure of the unwanted signal coupling between pairs in adjacent cabling from a transmitter at the near end into a pair measured at the far end.

alien near-end crosstalk (ANEXT) loss A measure of the unwanted signal coupling between adjacent cabling from transmitters at the near end into a pair measured at the near end.

all dielectric self-support (ADSS) A type of aerial optical fiber cable that is nonconductive/nonmetalic and requires no messenger strand for installation.

all-threaded-rod (ATR) A straight section of fully threaded round rod stock. Also called a threaded rod.

alternate entrance A supplementary entrance facility into a building using a different routing to provide diversity of service and for assurance of service continuity. (TIA)

alternate route A secondary communications path used to reach a destination. See also diverse route.

alternating current (ac) Electric current that alternates periodically (usually sinusoidal) in magnitude ahd direction. Contrast with direct current (dc).

alternating current equipment ground (ACEG) A conductor installed from the equipment grounding busbar inside an electrical panel to a telecommunications grounding busbar or telecommunications main grounding busbar.

ambient sound level The level of acoustic noise existing at a given location (e.g., room, area). Ambient noise level is measured, in accordance with NFPA 72®, National Fire Alarm Code', with a sound level meter as the root mean square, Aweighted, sound pressure level measured over the period of time that any person is present or a 24-hour period, whichever time period is the lesser.

American National Standards Institute (ANSI) cutout A standard or stock cutout furnished on doors and frames from the door or frame manufacturer.

American wire gauge (AWG) A system used to specify wire size. The greater the wire diameter, the smaller the AWG value. Historically, the AWG number has represented the number of drawing processes applied to a given wire.

ampacity The current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.

ampere (A, amp) A unit of measurement of electric current. One ampere is equal to the current produced by one volt flowing through a resistance of one ohm.

amplifier A device that increases the power level (amplitude) of an analog signal (waveform). Amplifiers boost the power in its assigned frequency range, including the intended signal and any induced noise.

amplitude The maximum absolute value reached by a voltage or current waveform.

amplitude modulation (AM) Modulation in which the amplitude of a carrier wave is varied in accordance with some characteristic of the modulating signal.

analog See analog signal.

analog input (AI) A device (e.g., temperature sensor) that sends a continuously variable signal to a building automation system controller.

analog output (AO) A device (e.g., damper actuator) that receives a continuously variable signal from a building automation system controller.

analog signal An analog signal is a continuous function of time. Contrast with digital signal.

anchor 1. A fastening device. 2. In an outside plant environment, a device made up of a single plate or series of flat plates and combined with a rod having a connecting eye.

anchor rod The portion of an anchor assembly that extends above the anchor plate below ground level to a point above ground level.

angle polished connector (APC) An optical fiber connector polished at an angle of 8 to 10 degrees to the fiber axis (the critical angle) to reduce the backreflection of the signal. Some high-performance singlemode systems (e.g., high bandwidth analog video systems) require a very low level of back-reflection (-55 dB or better) to perform correctly.

annular space A space between penetrating item and inside wall of penetration.

annunciator A unit containing one or more indicator lamps, alphanumeric displays, or other equivalent means in which each indication provides status information about a circuit, condition, or location.

antenna A conductive structure specifically designed to couple or radiate electromagnetic energy. In radio frequency systems, the antenna may be used to both transmit and receive electromagnetic energy.

antenna array (including panel) An antenna made up of a number of elements arranged in a periodic pattern including an active or driven element, a reflector, and a director. Array antennas may be narrowband or broadband, and are used in all frequency bands.

antenna entrance A pathway facility from the antenna to the associated equipment. (TfA)

antenna gain 1. A term used to describe the capability of an antenna to direct signal or reshape energy in a particular direction. 2. The ratio of the power required at the input of a loss-free reference antenna (usually an isotropic radiator or dipole) to the power supplied to the input of the given antenna to produce, in a given direction, the same field strength at the same distance. Antenna gain is usually expressed in decibels relative to an isotropic radiator (dBi) (isotropic reference).

antipassback A method for providing one card one-way access into and out of a secure area. It prevents someone from using a card to enter a secure area and then passing that card back to another to enter that same area.

aperture size 1. The effective capture area of an antenna. The term is commonly used in connection with microwave horn antennas and waveguides. 2. The physical size of the opening in a camera lens, expressed as F-stops.

apparatus A finished combina6on of devices (or equipment) intended to be placed on the market as a single commercial unit.

apparatus closet See telecommunications room.

AppIeTalk A proprietary network protocol stack developed by Apple Computer that allows LAN functionality such as file and print sharing. Its primary features are autoconfiguration and ease of use.

application address An address used to uniquely identify each software process running on a network device. See also medium access control (MAC) address and network address.

Application layer The Open Systems Interconnection Reference Model layer responsible for providing mechanisms that enable software applications on different systems to use the services of a network to exchange information. Also called Layer 7.

application sharing The process of running a software program on one station and allowing users at other stations to see and optionally control the application over the network.

application software Software used to perform a specific task (e.g.,.word processing, spreadsheet analysis, database management).

application specific cabling Cabling installed to meet the requirements of a specific transmission system or application.

approved ground A grounding (earthing) source approved for use by the authority having jurisdiction. See also earth ground and ground.

aramid A material with exceptional tensile strength and coefficient of thermal expansion near that of glass. Widely used as a strength member in optical fiber cables. See aramid yarn.

aramid yarn A strength element used in optical fiber cable to provide support and additional protection of the fiber bundles. See also aramid.

arbitration 1. A method of negotiation used in resolving disputes between parties. 2. The process of determining which requesting device will gain access to a resource. (IEEE)

arbitration loop (AL) A link that connects all disk drive nodes together and manages with a token acquisition protocol.

architectural assemblies Walls, partitions, or other barriers that are not load bearing. (TIA)

architectural drawing A two-dimensional graphical representation of a building, space, or object prepared with adequate detail to convey design information in a manner to serve as a guide for construction thereof.

architectural, mechanical, electrical, structural (AMES) Drawings or blueprints that include AMES designs.

architectural structures Walls, floors, floor/ceilings, and roof/ceilings that are load bearing. (TIA)

archive Collection and storage of data, records, or information.

armoring Method used for protecting cables against crush, impact, rodents, etc. Can be achieved through the use of corrugated steel, fiber-reinforced polymer rods, steel wire, glass yarns, or other suitable materials under or over the outer sheath of the cable.

arrester A device placed from phase to ground whose nonlinear impedance characteristics provide a path for high-amplitude transients. (Heneveld's Pocket Guide to Residential Technology Terms and Definitions)

asbestos Fibrous mineral substance used in buildings as insulation between the mid-1940s and 1978 and later found to be carcinogenic (cancer causing).

as-built The documentation of measurements, location, and quantities of material work performed. May be in the form of marked up documents or other work order forms.

aspirator An apparatus for producing suction: moving or collecting materials by suction.

asymmetric digital subscriber line (ADSL) Adigital service designed to provide high data transfer rates over traditional telephone cable. Asymmetric refers to different speeds for uplink and downlink traffic. See also digital subscriber line (xDSL).

asymmetric full-duplex A transmission process that allows different sending and receiving transfer rates to coexist on the same path for Ethemet video-on-demand.

asymmetric key cryptography See public key encryption.

asynchronous communication See asynchronous signaling.

asynchronous signaling A form of signaling in which each data character is coded as a string of bits. The bits are separated by start character and stop character bits. See also asynchronous transmission, isochronous communication, synchronous communication, and synchronous transmission.

asynchronous transfer mode (ATM) A high-speed network switching protocol that utilizes fixed-length (53 byte) packets, called cells, to carry all types of traffic (e.g., voice, data, still image, audio/video).

asynchronous transmission See asynchronous signaling.

attached resources computing network (ARCnet) A 2.5 Mbls or 20 Mb/s logical token-bus network configured in either a physical star or daisy chain.

attachment unit interface (AUI) The name used by the IEEE 802.3 standard for the cable that connects the media attachment unit to a 10 Mbls network device. This cable is equipped with a 15-pin connector. The corresponding 15-pin connector on an attaching device often is called an AUI connector.

attenuation The decrease in magnitude or the power loss of a signal that propagates between points, expressed in dB as the ratio of received signal to transmitted signal level. See also insertion loss.

attenuation-to-crosstalk ratio (ACR) The ratio obtained by subtracting insertion loss (attenuation [dB]) from near-end crosstalk (dB). ACR is normally stated at a given frequency. See also bit error rate (BER) and signal-to-noise ratio (SNR).

attenuator A device used to reduce the amplitude of an electrical signal without introducing appreciable distortion. audible signal Sound made by one or more audible notification appliances (e.g., bells, horns, speakers) in the response to the operation of any manual or automatic electronic device.

audio Something that is heard or having to do with something that is heard as sounds in the audio frequency range, which the average human can detect; in audio/video, having primarily to do with the process of reproducing sounds through a system of electronic components.

audio frequency (AF) The band of frequencies (approximately 20 Hz to 20 kHz) corresponding to a normally audible sound wave. Contrast with voice frequency (VF).

audit trail A sequential record that accounts for all the activities of an access control system. This record allows for the analysis of events over a given time period.

aught Colloquial term for numerical symbol "0" that is used in the numbering scheme for conductors larger than 0 AWG [8.3 mm (0.33 in)] (e.g., 2/0 AWG [13.41 mm (0.528 in)] is two aught).

augmented category 6 See category 6, augmented.

aural ear protectors Resemble ear muffs; available in passive or active models. See ear protector.

authentication A security mechanism that confirms the identity of a user accessing the network.

authentication, authorization, and accounting (AAA) Three network administration activities that are often tied together in a single network protocol/server (e.g., Internet Engineering Task Force remote authentication dial-in user service standard). See also the individual entries for authentication, authorization, and accounting.

authority having jurisdiction (AHJ) The entities responsible for interpretation and enforcement of local building and electrical codes.

authorization The process of establishing and enforcing the network activities that are permitted for a given user.

authorization level A security rating that must be met before access to a secure area can be granted.

authorization profile See access control list (ACL).

authorized passage device (authorized egress device) A device that, when activated, allows authorized persons to enter or exit monitored and controlled openings without triggering an alarm. The authorized passage device may be a keyed switch, card reader, or digital code reader.

automatic call distributor (ACD) A voice switching device that provides highly specialized call handling capabilities normally associated with call centers and other high-volume applications. Typically has extensive automated attendant functionality and computer-telephony integration features.

automatic gain control (AGC) A process or means by which gain is automatically adjusted in a specified manner as a function of a specified parameter (e.g., received signal level).

autonegotiation (AUTONEG) A feature that determines link options and optimal settings for a given connection. When AUTONEG is enabled, a network interface card can determine the capabilities of the device at the far end of the link and select the best mode of operation.

autorange Automatic ranging by an optical time domain reflectometer.

autosetup A capability where the test instrument automatically sets the testing parameters to appropriate levels for the component under test. Also called autoranging or automode.

autotest A function used by field test instruments to run all the required tests in a sequential manner without operator intervention.

auxiliary disconnect See auxiliary disconnect outlet (ADO) and auxiliary disconnect outlet (ADO) cable.

auxiliary disconnect outlet (ADO) 1. An extension of a demarcation point from a common owner's space into a tenant's individual space. 2. A device usually located within the tenant or living unit used to terminate the ADO or backbone cable (TIA).

auxiliary disconnect outlet (ADO) cable 1. The cable that extends the demarcation point in a common owner's space to a tenant's individual space. 2. In residential applications, the cable from the auxiliary telecommunications disconnect outlet/connector or the distribution device in a customer's premises to the backbone facility or the point of demarcation. (TIA).

availability A measure of network response time or freedom from operating failure (downtime) during a given period of time.

availability attack The disruption of network operations by maliciously generating enough traffic to cause congestion and thereby rendering the network unavailable to intended users.

average power (PA) Sustainable or usable portion of electrical energy in an alternating current over some amount of time. For sinusoidal signals, it is the peak power (PP) multiplied by .707 (e.g., 100 watts of PP is approximately equal to 71 watts of PA). See also power and peak power.

backboard - A panel (e.g., wood, metal) used for mounting connecting hardware and equipment.

backbone - 1. A facility (e.g., pathway, cable, conductors) between any of the following spaces: telecommunications rooms, telecommunications enclosures, common telecommunications rooms, floor-serving terminals, entrance facilities, equipment rooms, and common equipment rooms. (TIA) 2. In a data center, a facility (e.g., pathway, cable, conductors) between any of the following spaces: entrance rooms or spaces, main distribution areas, horizontal distribution areas, and telecommunications rooms.

backbone bonding conductor - A copper conductor extending from the telecommunications main grounding busbar to the farthest floor telecommunications grounding busbar. (TIA) See also telecommunications bonding backbone interconnecting bonding conductor (TBBIBC).

backbone cable - See backbone and backbone cabling.

backbone cabling - Cable and connecting hardware that provide interconnections between telecommunications rooms, equipment rooms, and entrance facilities. See also backbone.

backbone loop diversity - SA type of loop diversity that assigns circuits among different intrabuilding backbone cables.

backbone network An intermediate data network connecting two or more LANs. See also internetwork.

backbone pathway - The portion of the pathway system that permits the placing of main and high-volume cables between the entrance location and all cross-connect points within a building and between buildings.

backbone raceway - See backbone pathway.

back end equipment - The equipment component of a distributed antenna system that is located in an area of coverage and receives and transmits signals to the headend.

backfill - Earth placed outside foundation walls, or in cable trenches, for filling and grading back to a finished state.

backplane - See switch matrix.

backpressure - A flow control mechanism used to pause data transmission.

backscatter coefficient The ratio of backscattered light to transmitted light. The backscatter is a fixed percentage of the transmitted light.

backup - A copy of the data stored on a device.

backup path - A secondary or alternate channel for signal flow. It is typically used when there has been a failure of the main (primary) path.

backup storage - The ability to provide the means to recover from primary storage failure and the corresponding loss of data, a process typically referred to as disaster recovery. See also disaster recovery.

BACnet - See building automation and control network (BACnet®).

BACnet broadcast management device (BBMD) - A BBMD is one of the BACnet/IP broadcast management methods outlined in ISO 16484-5. This standard incorporates all amendments to ANSI/ASHRAE Standard 135 since 1995.

BACnet® interoperability building block (BIBB) - The purpose of a BIBB is to simplify interoperability into common functions that are intuitive to specifiers and owners and then define a name and set of simple BACnet requirements for each.

BACnet® Testing Laboratories (BTL) - The BACnet Manufacturer's Association offers a product testing and listing program for building automation products that have BACnet capability. Laboratories that conduct such testing and listing services are known as the BACnet Testing Laboratories.

BACnet® virtual link layer (BVLL) A BACnetllntemet protocol communication is implemented by defining a new protocol layer called the BACnet virtual link layer. The BVLL provides the interface between the BACnet Network layer and the underlying capabilities of a particular communications subsystem.

badge reader - See card reader.

badging software - Security software that is capable of creating a photo identification badge.

balanced cable Two or more insulated pairs of wires-identical in composition, size, and length-uniformly twisted together.

balanced copper cable - A cable consisting of one or more copper symmetrical cable elements (twisted-pairs or quads). See also balanced cable.

balanced line A transmission line that consists of a balanced cable pair whose transmit and receive voltages, at any point on the line, are equal in magnitude but opposite in phase with respect to ground.

balanced twisted-pair cable - See balanced cable.

balloon float - A helium filled balloon device used to assist in the verification of line of sight in point-to-point radio communications

balun - A balanced-to-unbalanced circuit coupling device, used to convert from unbalanced to balanced transmission, and provides impedance matching for connecting twisted-pair to coaxial cable.

bandwidth 1. A range of frequencies available for signaling expressed in hertz. 2. The information handling capability of a medium, expressed in units of frequency (hertz).

bar code card An access control card with identification information encoded in the bar code format.

barrel connector A female-to-female adaptor used to join two connectorized segments of coaxial cable together.

base Describes the number of signals traveling over media at the same time. Base is a shortened form of baseband, which has only one carrier channel and no multiplexing.

baseband An unmodulated, nonmultiplexed digital signal that by definition occupies the entire media bandwidth during each transmission. Baseband transmissions using multiplexing techniques are generally referred to as digital broadband. See also broadband.

baseboard pathway A distribution method in which channels containing cables run along or within the baseboards of a building or modular furniture.

basefining 1. The process of defining and documenting existing network characteristics. 2. A term used to describe the top view of surveyed terrain with elevations, benchmarks, natural features, and existing structures.

base station (BS) The fixed part of a mobile radio frequency network through which mobile and portable terminals (or stations) communicate. In the cellular industry, this may be called a base transceiver station.

basic link test configuration Obsolete term. Refer to permanent link.

basic rate interface (BRI) An integrated services digital network interface standard that consists of two B-channels and one 16 kb/s D-channel.

basic service set (BSS) - A single wireless LAN access point and its associated clients, loosely equivalent to a wireless collision domain.

battery backup A secondary energy source used to power devices in the event the primary energy source fails.

baud The measure of how often a signal can be changed from one electrical state to another in one second. Used to describe low-speed transmissions and is not common in modern baseband or broadband systems.

bay - 1. A regular repeated spatial architectural element defined by beams, columns, or ribs and their support. 2. Floor-standing racks, frames, or cabinets to house telecommunications or equipment.

Bayonet Neill-Concelman (BNC) See BNC connector.

beacon 1. A device used to mark tower for aircraft avoidance. 2. A frame transmitted by wireless LAN access points at regular intervals to let its presence be known to clients within its transmit range.

beacon frame A special token ring frame that is transmitted by a network device when it detects a ring failure. The device sending the frame is said to be beaconing.

beam clamp A device attached to a building structure to hold cable supports or equipment.

beam width On an antenna radiation pattern for a particular plane, the angle between the half-power (3 dB) points of the main lobe, when referenced to the peak effective radiated power of the main lobe. Beam width is usually expressed in degrees.

bearing plate A steel plate placed under one end of a beam, column, or truss at a support point for load distribution.

bearing wall A wall supporting a load other than its own weight. (TIA)

be A logarithmic ratio of analog signal strengths; named in honor of telephone pioneer Alexander Graham Bell. bend loss A form of increased attenuation caused by (a) having an optical fiber curved around a restrictive radius of curvature or (b) microbends caused by minute distortions in the fiber imposed by externally induced perturbations.

bend radius The radius of curvature that a media can bend without signal degradation.

berm The stabilized or paved area of the shoulder.

bias tee A type of connection used to inject dc power to combine the ac radio frequency signal on one end of a coaxial cable, and tap it off at the other end, thereby allowing remote powered devices to operate without a separate local power source.

biased door contacts A high-security door contact that uses a "biasing" magnet mounted inside the read switch part of the door contact package.

biconic A type of optical fiber connector developed by AT&T; exists in multimode and singlemode versions.

bid form bid form A prepared document that the bidder will submit to the tracking agent, owner, or contracting agent

bidders' conference A meeting conducted by the issuer of a request for quote or request for proposal to review and address any questions from respondents (bidders) with regard to the bid documents.

bidding documents All construction documents issued to bidders before the signing of an owner-contractor agreement.

bidirectional signaling Signals that pass in opposite directions between two transmitters. In a twisted-pair cable, this may be on the same or different pairs. Wireless and optical fiber systems also may operate in a bidirectional manner. Contrast with unidirectional signaling.

bill of material (BOM) A list of the quantity and specific types of materials to be utilized on a project. This list also should consider exempt materials (e.g., screws, bolts).

binary A numbering system using a base number of 2. Digital signals may be described as binary signals. When only two states or conditions are present, they are typically represented as on/off, open/ closed, ground/open, high/low, yes/no, or positive/negative. When printed out, they are typically expressed as one (1) and zero (0).

binary digit (bit) 1. The smallest unit of information in digital systems. 2. Zeros and ones used to represent data processed by digital devices.

binary digital system A system in which the data rate is determined by the baud rate and the number of bits encoded per baud interval.

binary phase shift keying (BPSK) A modulation scheme using phase-shift keying between two phase states, normally 180 degrees apart.

binder A tape or thread used for holding assembled cable components in place.

binder group One of two or more bound copper pairs or optical fiber strands within a cable.

biometrics An automated method of recognizing a person based on physiological or behavioral characteristics.

bipolar signal A signal that assumes both positive and negative voltage values. Many bipolar coding schemes attempt to minimize radiated emissions by alternating polarities (causing the signal to sum to zero over time).

bipolar violation Two pulses of the same polarity in a bipolar coding scheme that normally requires alternate signal pulse polarities. A bipolar violation may be an error condition or may indicate a special state in the coding scheme.

-bis A suffix applied to a protocol that identifies the second version of the protocol (e.g., V.32bis).

bit 1. The basic unit of digital information, used to indicate the existence of one of two binary states or conditions (e.g., current flow or no current flow, on or off). 2. A digital pulse representing a one (1) or a zero (0); contracted from the phrase "binary digit." 3. A binary digit; the smallest element of information in binary systems. It is either a logical one (1) or zero (0), also called "an on or an off bit" of binary data.

bit error rate (BER) 1. The ratio of incorrectly transmitted bits to total transmitted bits. A primary specification for all transmission systems, it is usually expressed as a power of 10. The number of errors made in a digital transmission as compared to complete accuracy. 2. The fraction of bits transmitted incorrectly. See also attenuation-to-crosstalk ratio and signalto-noise ratio.

bit per second (bls) A unit of measure used to express the binary data transfer rate of a device, system, or communications channel. Also called bit rate.

bit rate Transmission of a binary signal measured in bits per second.

bit stream A series of binary digits and ones} representing the message being transferred between devices.

bit time The inverse of the data transfer rate. See also data transfer rate.

bit-8 zero substitution (B8ZS) A bipolar coding scheme in which successive "1s" are sent as voltage pulses with alternating polarity. Additionally, a bipolar violation is intentionally sent for an eighth consecutive "0," in order to meet a minimum number of pulses required to maintain network synchronization. B8ZS line coding is most commonly found with T1 and integrated services digital network basic rate lines.

blank cell The hollow space of a cellular metal or cellular concrete floor unit without factory installed fittings. (TIA)

blended floor system A combination of cellular floor units with raceway capability and other floor units with raceway capability, systematically arranged in a modular pattern. (TIA)

block (connecting) See connecting hardware.

blueprint A reproduction of an architectural plan and/or technical drawing that provides details of a construction project or an existing structure.

Bluetooth© A low-power radio frequency personal area network technology that enables cordless data transfer between Bluetooth equipped devices at short range.

BNC connector A coaxial connector with twist-on bayonet locking coupling.

bolt position switch A miniature switch used on or in a locking device to monitor whether the locking bolt is in the locked (projected) or unlocked (retracted) position

bond 1. An electrical connection using a low-resistance path. 2. A written obligation under seal to guarantee that specific documents are accurate or that the bonded party will meet specific requirements, in a specific way, within a specific time period.

bonded pair Design that affixes two insulated conductors together.

bonding The permanent joining of metallic parts to form an electrically conductive path that will ensure electrical continuity and the capacity to conduct safely any current likely to be imposed. (TIA)

bonding conductor (BC) A conductor used specifically for the purpose of bonding.

bonding conductor for telecommunications (BCT) A conductor that interconnects the building's service equipment (power) ground to the telecommunications grounding system.

booster An amplifier inserted into a cable to increase the signal amplitude in order to compensate for signal loss due to attenuation.

boring A method to displace earth under the ground without breaking the ground surface (trenching) or cutting ground surfaces (e.g., sidewalks, driveways, parking lots, road surfaces). Normally, as dirt is displaced or removed, conduit is inserted.

borings Sample cylinders of subsurface material, taken at varying depths, to determine the character of the bearing material.

bottom-up design See physical design process.

bounded medium A term used to describe cabling or waveguide. Contrast with unbounded medium.

braid A group of non-insulated conductors interwoven to surround one or more insulated conductors. (TIA)

branch A cable run in a coverage area that connects one or more building automation system devices.

branch access A form of resource access where connection to a LAN is made from a LAN-connected station at another organizational site using a telecommunications link.

branch splice A splice in which one cable is spliced to multiple cables.

breakout An optical fiber cable that has an individual jacket for each tight-buffered fiber.

bridge A Layer 2 networking device used to connect separate LAN collision domains (or network segments) to extend network reach or selectively isolate network traffic.

bridged jack A dual-position modular female jack where all pins of one jack are permanently bridged to the other jack in the same order. (TIA)

bridged tap A connection that enables multiple appearances of the same cable pair at several distribution points. (TIA)

bridging A method to connect multiple devices or cables to a single appearance of a connection.

bridging (architectural) A system of bracing between floor beams to prevent lateral instability.

bridging clip An encased or bare metal clip utilized to couple cable conductors on a connecting block and provide a point of physical disconnection.

bridle ring A ring that is circular in shape but is open rather than closed. It has a pointed shaft at its apex that is threaded for installation into wood or prethreaded devices.

broadband 1. An analog design simultaneously using multiple communication channels separated by guard bands. 2. Sometimes used to describe a highspeed digital signal associated with backbone or multiplexed transmissions.

broadcast A technique for sending data simultaneously to all devices attached to a network with a single transmission. See also multicast and unicast.

broadcast domain The span of a LAN as represented by the devices capable of receiving a Network layer datagram addressed to all.

broadcast storm A series of retransmitted broadcasts caused by uncontrolled duplication of the original message.

browser Applications software used to access Web-based content.

browser mode A form of remote access where the remote station accesses LAN resources through a Web server on the LAN and obtains access to resources designed to operate in a Web browser environment. Contrast with control mode, terminal mode, and transparent mode.

bucket lift Personnel lift composed of a large bucket mounted on the end of an extendable arm in which the user stands.

buffer A temporary storage area in a networking device used to hold incoming data until it can be processed.

buffer coating A protective thermoplastic material that is applied to the acrylate layer of the optical fiber to protect against environmental hazards. May be more than one layer. See also coating.

buffer tube A supplemental loose-fitting cover, which is applied over the primary coated optical fibers at the time of installation.

buffering The process of providing a supplemental air supply to pressurized cables during splicing operations.

building automation and control network (BACnet®) An industry standard protocol for building automation and control networks developed under the auspices of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE), published as ANSI ASHRAE standard 135-2004. BACnet defines a four-layer architecture that includes the Physical, Data Link, Network, and Application layers of the Open Systems Interconnection Reference Model (ISO 7498).

building automation system (BAS) Equipment and telecommunications infrastructure that supports monitoring, control, operation, and management of building services. (TIA)

building automation system outlet A connecting device between a horizontal cable and a coverage area device. (TIA) building code Construction requirements that are adjudicated into law by the authority having jurisdiction.

building core A three-dimensional space, permeating one or more floors of the building and used for the extension and distribution of utility services (e.g., elevators, washrooms, stairwells, mechanical and electrical systems, telecommunications) throughout the building. (TIA)

building distributor (BD) A distributor in which the building backbone cable(s) terminate(s) and at which connections to the campus backbone cable(s) may be made. International equivalent term for intermediate cross-connect.

building entrance The point where services media enter or leave the building. See also entrance room or space (telecommunications) and entrance facility (EF [telecommunications]).

building entrance facility (BEF) See entrance facility (EF [telecommunications]).

building entrance protector A device or devices used to terminate cables entering or leaving buildings. It provides a housing for the voltage and currentlimiting modules to protect the cable pairs from lightning and foreign voltage and/or current.

building entrance terminal Cable termination equipment 'used to terminate outside plant cables at or near the point of building entry.

building grounding electrode system A network of grounded building components (e.g., metal underground water piping, metal building frame, concrete-encased electrode, a ground ring and rod, pipe electrodes) that is used or can be used for grounding/earthing purposes.

building module The standard selected as the dimensional coordination for the design of the building. The international standards have established a 100 mm (4 in) basic module. This produces modular coordination to all building materials, products, and utilization of the floor space.

building plan The representation of a building project.

building signaling system See building automation system.

building specification The detailed written description of a building project. Bull-Line TM See pull rope.

bullwheel A large wheel used to maintain an arc when feeding large cables into a backbone pathway.

bundle 1. Many individual optical fibers contained within a single jacket or buffer tube. Also, a group of buffered optical fibers distinguished in some fashion from another group in the same cable core. 2. Also used to indicate time and common handling of multiple cables routed together.

bundled cable An assembly of two or more cables continuously bound together to form a single unit. (TIA) Contrast with hybrid cable.

bundled fiber Group of buffered optical fibers distinguished in some fashion from other groups.

buried cable A cable installed under the surface of the ground in such a manner that it cannot be removed without disturbing the soil. (TIA) See also direct-buried cable and underground cable.

buried entrance An entrance facility in which cables enter or leave the building below grade rather than running in conduit.

burn-in Running devices prior to their use in service.

bursty A characteristic of digital transmission where the transmission rates have large variations during short periods of time.

bus topology (physical) 1. Networking topology, in which each communications device or network has a single connection to a shared medium that serves as the communications channel. Also called a point-to-multipoint topology. 2. A linear configuration where all network devices are connected using a single length of cable. It requires one backbone cable to which all network devices are connected.

butt configuration A configuration where one or more cables enter the splice case (end cap) from the same direction.

butt set See telephone test set.

butt splice A splice in which one or more conductors enter the module or connector from the same direction.

butterfly detail A maintenance hole diagram showing all four walls and detailing route and splicing locations of cable passing through the maintenance hole.

byte A data unit made up of eight bits. Also called an octet.

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.

daisy-chaining - A physical topology for wiring devices in sequence.

dark fiber - An optical fiber strand that is not in use and may or may not be terminated.

data - Electronically encoded information. (TIA)

data center - A building or portion of a building whose primary function is to house a computer room and its support areas.

data communication - The transmission and reception of electronically coded information.

data compression - Enables devices to transmit or store the same amount of data in fewer bits.

Data Encryption Standard (DES) - Uses 40 and 56 bit keys to encrypt text into 64 bit blocks. (ANSI)

datafill - Contents of the fields and tables in the system software load that determine the operational configuration.

datagram - A piece of message sent over a packet switching network containing the address.

datagram service - A network on which the delivery of messages is not guaranteed; rather, messages are delivered on a best-effort basis.

data integrity - 1. The assurance that a given data retains its original meaning and value and has not been corrupted. 2. The degree in which a collection of data is complete, consistent, and accurate. (IEEE)

Data Link layer - The Open Systems Interconnection Reference Model layer responsible for providing reliable data transfer in the form of frames on a LAN. Also called Layer 2.

Data Link layer address - See medium access control (MAC) address.

data network - An interconnected system of computers, peripherals, and software over which commands, files, and messages are sent and received.

data protection - Techniques used to guard the confidentiality, integrity, and availability of data.

data rate - The number of bits of information transmitted per second.

data service unit (DSU) - A customer premises device that frames and channelizes the user's data for transmission on the digital network.

data terminal equipment (DTE) - 1. The term used in the IEEE 802.3 standard to refer to a station (computer) or port that serves as the data transmission source, data transmission destination, or both, for the purpose of sending or receiving data over the network. 2. A device producing data to be transmitted across an intemetwork.

data transfer rate - The rate at which information is transferred between network devices over a communications channel. Also called throughput or operating speed.

data vaulting - The process of storing a backup of organizational data at a different geographic location than the original. This location should be where it can be protected from hardware failure, theft, fire, and other similar threats.

DB## connector - A connector widely used for connections between data equipment, available in a variety of configurations (e.g., DB15, DB25). Also called a D-subminiature connector.

dB(A) - Decibels (dB) above reference noise, adjusted for frequency (with F1A weighting). Adjusted reference noise is equivalent to a 1004 hertz (Hz) test tone at --85 dBm.

dBi - Decibel levels referenced to a theoretical isotropic antenna. Used to express antenna gain.

dBm - 1. Decibel referenced to 1 milliwatt (mW); 0 dBm is equal to 1 mW; -10 dBm corresponds to 0.1 mW; -20 dBm corresponds to 0.01 mW; -30 dBm corresponds to 0.001 mW. 2. Psophometrically weighted noise power in decibels, with respect to a power level equivalent to an 800 Hz test tone at 0 dBm.

DBmOp - Psophometrically weighted noise power in decibels, with respect to a power level equivalent to an 800 Hz test tone at 0 dBm.

dBmV - Decibel referenced to 1 millivolt often used in cable antenna television installations across 75 ohms.

dBrnc - Decibels above reference noise (with C-message weighting). Reference noise is equivalent to a 1004 Hz test tone at-90 dBm.

dBu - Decibel referenced to 0.775 volt (V); 0 dBu is equal to 0.775 V (rms).

dBV - Decibel referenced to 1 volt (V); 0 dBV is equal to 1 V (rms).

deadbolt - A bolt operated manually and nonactuated by springs. When locked, the bolt cannot be forced back. A deadbolt is operated (projected and retracted) by a key cylinder or lever handle.

deadend - Guying placed at the end of a pole line run or at corners.

dead latch - A latch in which the latch bolt is positively held in the projected position by an auxiliary mechanism.

dead zone - The distance on a length of optical fiber following a Fresnel reflection (event) in which an optical time domain reflectometer cannot detect additional events.

decibel (dB) - A logarithmic unit for measuring the relative voltage, power (in watts) or strength (in voltage or current) of a signal. A decibel is one tenth of a bel. See also bel.

dedicated in-floor service fitting - See insert.

dedicated LAN - A network on which a separate communications channel is assigned exclusively to each device by using switching technologies.

de facto standard - An informal standard resulting from popular acceptance of a product or practice.

degradation - The decline in operational performance.

de jure standard - A standard formally documented by a committee responsible for establishing its specifications.

delay on break - A term used to describe a mode of operation relative to timing devices. The delay begins when the initiate switch is opened (delay break of initiate switch).

delay on energization - A term used to describe when the initiate switch is closed for application of power to the input.

delay skew - The difference,in propagation delay between the pair with the highest and the pair with the lowest propagation delay value within the same cable sheath.

delay spread - The standard deviation of the delay of reflections of a radio frequency wave that is weighted proportional to the energy in the reflected waves.

delayed egress - A delayed egress device allows a 15 second delay in opening a door required by building code to be equipped with panic or fire exit hardware.

delta (delta-connected) power system - A power system having none of the normal current-carrying conductors connected to ground.

delta power supply - A three-phase system with no grounded conductor connection.

demand priority - An arbitration scheme that provides network access on the basis of the priority level of the message or sending device.

demarcation point (DP) - 1. A point where the operational control or ownership changes. (TIA) 2. The point of interface between service providers and customer facilities.

demilitarized zone (DMZ) - network lobby network.

demodulation - The recovery of information from a modulated carrier of a signal having substantially the same characteristics as the original information.

demodulator - An electronic device that information from a modulated removes signal.

demultiplexer (DP) - A device that separates two or more signals that have been combined into a multiplexed signal.

demultiplexing - The process of reconstituting the individual channels from the composite signal.

depressed-clad - An optical fiber, usually singlemode, that has double cladding, with the outer cladding having a refractive index ratio between that of the inner cladding and the core. This reduces macrobending losses and provides lower dispersion over a wider wavelength range. Also called a dual clad.

design development (DD) - A design phase that follows a schematic design and is prior to construction documents.

design drawing - Graphical and textual information organized on a two-dimensional surface for the purpose of conveying data about a specific portion of a project. (Construction Specifications Institute, Uniform Drawing System, 1997)

design manual - A collection of guidelines, requirements, and accepted practices intended to cover design, installation, and administration of systems that fall within a defined scope.

design specification - Documentation that defines a goal or set of goals including specific performance and design parameters.

designation strip - Label that may be color coded, placed on terminal blocks, and used for identification (e.g., circuits).

design-build construction - A method of construction when a contractor is employed to both design and build a project.

despread - The process of filtering out or shrinking a digitally coded signal to its original form in the direct sequence (pseudo-noise) technology.

detail drawing - A detailed graphical representation of a specific area or element of construction, often not drawn to scale.

detector (optical) - An optoelectronic transducer that converts light to an electrical signal.

Deutsche Industries Norm (DIN) - The German Institute for Standardization is a registered association recognized by the German government as the national standards body and represents German interests at international and European level standards forums.

device (protection) - A protector, protector mount, protector unit, or protector module.

device (work area) - A telephone, personal computer, graphic or video terminal, or building automatic control.

device address - An address to uniquely identify each device on a network. The address is coded in the physical hardware. See also network address and medium access control (MAC) address.

device box - See outlet box (telecommunications).

dialer - 1. Software used by remote stations to connect to the network over telecommunications circuits. Also called remote client software. 2. A standalone device used with alarm systems to dial-out to a central monitoring station.

dibit (data transmission) - Two bits; two binary digits. (IEEE)

digital - See digital signal.

die - A steel block or plate with small conical holes through which wire is drawn.

dielectric - A material that is nonmetallic and noncenductive used to insulate a conductor.

dielectric cable - A nonconducting cable (e.g., optical fiber cable with no metallic members).

dielectric constant - A unit of relative electric permittivity of an insulator.

differential-mode (DM) circuit - The closed circuit for the intended signal current.

differential-mode (DM) voltage - The symmetrical noise voltage that appears equally and in opposite phase in each active signal-carrying conductor. Contrast with common-mode voltage.

diffraction - The bending of radio, sound, or lightwaves around an object, barrier, or aperture edge.

digital alarm communicator system (DACS) (dialer) - A system in which signals are transmitted from a digital alarm communicator transmitter (DACT) located at the protected premises through the public switched telephone network to a digital alarm communicator receiver so that it may seize the line to which it is connected. The seizure disconnects any private telephone equipment beyond the DACT's point of connection.

digital certificate - A security tool used to authenticate a message. It ensures the recipient that the message originated from a source whose identity has been verified by the issuer of the certificate.

digital color code (DCC) - A specific code used to identify analog cell sites. (Nortel)

digital enhanced cordless telecommunications (DECT) - A standard developed by the European Telecommunication Standards Institute. DECT defines the radio connection between two points and can be used for remote access to public and private networks.

digital input (DI) - The input to a device that receives a digital signal from an output device.

digital key - A bit sequence used by a security tool to encrypt a message prior to transmission to keep its contents confidential and used by the recipient to restore the encrypted message. See also key.

digital output (DO) - The output of a device that sends a digital signal to an input device.

digital signal - A signal that encodes information in the form of a sequence of discrete states. For example, a binary signal uses two states to encode the two states (0,1). Contrast with analog signal.

digital signature - A bit sequence used by a security tool to authenticate a message. It ensures the recipient that the message was not modified after being transmitted by the sender.

digital subscriber line (xDSL) - A family of digital technologies designed to provide a variety of data transfer rates using different encoding and delivery methods. See also asymmetric digital subscriber line.

diplexer - A three-port frequency-dependent device that may be used as a separator or a combiner of signals. Duplex transmission through a diplexer is not possible. (ATIS)

diplexing - Diplexing is combining the output of two or more transmitters into a single antenna system or the reception of two or more signals of different frequencies.

dipole array - See antenna array.

dipole - An antenna formed by splitting two wires of a two-wire transmission line, and bending them back to form a single straight line. The antenna feed is in the middle of the dipole antenna, where the split occurs. A dipole antenna is a resonant antenna. The optimal length of a dipole antenna is one half of the wavelength of the signal being received or transmitted by the antenna. A dipole antenna is a narrowband antenna, operating efficiently in only a narrow band of frequencies.

direct attached storage (DAS) - The combination of a high-speed interface and shared disk drives, where the disk drives are connected directly to the serversinternally or externally.

direct broadcast satellite (DBS) - A service that uses satellites to broadcast multiple channels of television programming directly to a small-dish antenna.

direct connection - The act of connecting a cable to customer equipment without the use of a patch panel or terminal block.

direct current (dc) - A constant-value electric current that flows in one direction in an electric circuit.

direct current (dc) loop resistance - Cable conductor resistance with the far end of the cabling shorted. This is the resistance for two conductors of a metallic cable.

direct digital control (DDC) - A control loop used in building automation systems in which a microprocessor-based controller controls equipment (e.g., air handlers, chillers, boilers) based on sensor inputs and set-point parameters according to a sequence of operations.

direct hold magnetic lock - An electric magnet is mounted to a doorframe opposite a metal plate. When energized, the lock bands to the armature and locks the door.

direct sequence spread spectrum (DSSS) - 1. A technique used to structure signal process utilizing a digital code sequence having a chip rate much higher than the information signal bit rate. Each information bit within a digital signal is transmitted as a pseudorandom sequence of chips. 2. Using a spreading code, the transmitted signal is spread over a wide frequency band. The spreading code is reapplied to the transmitted signal at the receiver.

direct sound - Sound that travels directly from a speaker to a listener without having undergone any reflection.

direct wave - Direct wave is the portion of the wave that travels from transmitting to receiving antenna. It is limited to the distance from the transmitter to the horizon, plus a small distance added by the wave's attempt to bend with the surface of the Earth.

direct-buried cable - A telecommunications cable designed to be installed under the surface of the earth, in direct contact with the soil. (TIA) Contrast with underground cable.

directional antenna - An antenna characterized by a broad coverage zone that preferentially sends or receives signals in a specific direction. See also omnidirectional antenna and unidirectional antenna.

directional coupler - A device with one input port and two or more output ports that splits a single signal to multiple outputs while providing a high attenuation for reverse signals.

directivity - The ratio of the maximum sensitivity of an antenna to its average sensitivity. It varies directly as the effective aperture of the antenna and inversely as the square of the wavelength.

directory - A database of the resources available on a network. Typically, it contains records far devices, software applications, data files, users, and groups.

disaster recovery - The procedures and actions taken to restore network operations after an event that destroys or disables some or all of the network. See also backup storage.

discone antenna - A development of the ground-plane antenna in which a circular disc is substituted for the monopole so that the antenna has a broadband response.

discrimination - The process of selecting the desired signal of the proper input level.

disk cache - An area of computer memory where data is temporarily stored on its way to or from a disk drive. See also caching.

disk duplexing - The simultaneous writing of all data to be stored onto two hard disks, where each hard disk is connected to a separate controller card.

disk mirroring - The simultaneous writing of all data to be stored onto two hard disks, where both hard disks are connected to the same controller card. If one of the hard disks fails, the other continues to provide storage services.

diskless workstation - A personal computer that depends upon a network server for loading data and applications. Diskless workstations are configured without a floppy or hard disk drive, thereby providing additional security.

dispersion - 1. The loss of signal resulting from the scattering of light pulses as they are transmitted through a medium. 2. The widening or spreading out of the modes in a light pulse as it progresses along an optical fiber. 3. The characteristics of the sound coverage field of a speaker.

dispersion shifted - A singlemode optical fiber that has a nominal zero-dispersion point at a wavelength of 1550 nanometer. Contrast with dispersion unshifted.

dispersion unshifted - A singlemode optical fiber that has a nominal zero-dispersion point at a wavelength of 1300 nanometer. Also called conventional or unshifted optical fiber.

distance vector algorithm - A network routing protocol that uses the number of hops (links between routers) to determine efficient routing, based on the Bellman-Ford algorithm.

distortion - A change in the shape of a signal's waveform.

distributed access control - An access control system in which all control decisions are made at the local controllers, independent from a host computer. Local controller events are uploaded to a host computer periodically for review and storage.

distributed antenna system (DAS) - Systems that transmit or relay radio frequency signals (e.g., signals from cellular/ personal communications system telephones, text pagers, wireless LANs) within buildings, structures, tunnels, or other areas where wireless services cannot be otherwise provided.

distributed queue dual bus (DQDB) - The DQDB IEEE 802.6 standard used in metropolitan area networks.

distribution cable - See horizontal cable.

distribution cell - The cellular floor sections from which cables emerge into work areas.

distribution device (DD) - A facility located within the dwelling unit for interconnection or cross-connection. (TIA)

distribution device cord - A telecommunications cord that extends between the distribution device and the auxiliary disconnect outlet. (TIA)

distribution duct - A raceway of rectangular cross-section placed within or just below the finished floor and used to extend the wires or cables to a specific work area. (TIA)

distribution frame - A structure with terminations for connecting the cabling of a facility in such a manner that interconnection or cross-connections may be readily made. (TIA)

distribution panel - A wiring board that provides a patch panel function and mounts either in a rack or on a wall.

distribution ring (D-ring) - Wire management ring shaped like the letter D for routing and supporting distribution cables and jumpers/patch cables on a backboard.

distribution system (DS) - A bridging engine in access points that is used to connect access points together. The connection can be wired or wireless.

diverse route - An alternative routing for cables and/or services to provide a different pathway for resilience or security. See also alternate route.

diversity reception - A technique used to improve the reception ability of a wireless network device (e.g., access point). A second antenna is built into the wireless device, which uses the antenna with the best reception.

divestiture - Transferring of title or loss of ownership as a result of government order, usually as a result of misdeed or in the interest of avoiding a monopolistic business environment.

Division 1 - A division in the Construction Specifications Institute MasterFormatT"" that standardizes the way information about a nonresidential construction project is organized. Division 1 is subordinate to the general conditions and supersedes part 1 of each section. (CSI)

door contact - A recessed or surfacemounted peripheral device that provides the electronic access control with an input that reports the status of a door or passageway that is being monitored.

door-forced alarm - An alarm generated when a door is forced open.

door held open alarm - An alarm generated when a door is held open beyond the designated period of time as programmed in the controller.

door position switch - A switch that is used to monitor whether a door is in an opened or closed position.

door switch - A switch that reflects the status of the door: open or closed.

dopant - An impurity added usually in minute amounts to a pure basic substance to alter its properties. In the manufacturing of optical fibers, dopant is used to increase the optical fiber core's refractive index to that of the cladding.

double-gang box - A device used to house telecommunications or electrical cabling for the purpose of attaching outlets and faceplate or cover that houses connectors for the interconnection of equipment. Its size is roughly twice that of a single-gang box.

down conductor - A conductor that connects air terminals to ground on the outside of a structure. Used with lightning protection systems.

down guy - A steel messenger (strand) that connects the suspension strand, span guy, or other items of aerial plant to an anchor and rod.

downlink - 1. Signals transmitted from satellites to ground stations. 2. In demand priority access method, the communications channel between a repeater and a connected end node or between a repeater and a lower-level repeater.

download - To send information from a host computer to a controller.

downtilt - A deliberate rotation of the antennas E-plane pattern (a common method used when co-channel interference is an issue). (Nortel)

downtime - The interval during which a functional system is inoperable.

draft international standard (DIS) - A draft version of a standard in which all member comments have been incorporated.

draft proposal - An International Organization for Standardization standard document that has been registered and numbered but not yet given final approval.

drag line - Pull cord or line installed in a cable pathway. The line may be used for pulling in a stronger strength rope to pull cable(s) of greater mass and weight into the finished conduits.

drain wire - A noninsulated conductor placed in electrical contact with a shield, acting as a coupled bonding conductor, and intended to optimize shielding effectiveness.

draw - Payment method for a project in which the contractor receives an initial payment on commencement of the contract and makes periodic draws during the term of the project.

drawing set - A set of drawings that shows the dimensions and the relationship between components of a building project.

dressing - Placing cables into a neat and symmetrical pattern for proper alignment and positioning for termination.

dressing block - A plastic receptacle used to form and hold connectors to allow wire termination.

drip loop - The length of cable, usually on the exterior of a building, placed above the entry point of the building, extended to below the entry point, and looped back up to the entry point of the structure. The use of such cable installation will impede moisture infiltration.

drop and insert - A process where a part of the information carried in a transmission signal passing through the repeater site is demodulated (dropped) to serve local consumers from the repeater site or information is inserted for further transmission.

drop cable - 1. A branch cable. 2. The cable allowing connection and access to and from the trunk cable of a network.

drop ceiling - See suspended ceiling.

drop wire - An aerial cable that connects a serving outdoor terminal to a building or structure.

dry contact - A switch or relay contact that is not connected to other voltage sources.

drywall - An interior wall construction consisting of gypsum or plasterboard.

D-subminiature connector - See DB## connector.

dual clad - See depressed clad.

dual foil - A secondary foil placed around foiled twisted-pair cable.

dual simplex link - A communications channel consisting of two signal paths, one in each direction.

dual-attachment concentrator (DAC) - A fiber distributed data interface concentrator that has four-fiber, dual link connections to both the primary and backup ring paths. Contrast with single-attachment concentrator.

dual-attachment station (DAS) - A fiber distributed data interface Class A station with four-fiber, dual link connections to both the primary and backup ring paths. If the primary ring breaks, the station will use the secondary .ring. Contrast with single-attachment station.

dual-duplex signaling - A form of bidirectional signaling in which data transfer can flow in both directions at the same time over a single communications channel. See full-duplex signaling, half-duplex signaling, and simplex signaling.

dual-ring topology - A ring topology that allows each device or network to have two connections to each adjacent device or network (e.g., SONET, fiber distributed data interface).

duct - 1. A single enclosed raceway for conductors, wires, or cables. See also raceway. 2. An enclosure in which air is moved. Generally part of the heating, ventilating, and air-conditioning system of a building.

ductbank (DB) - An arrangement of ducts, for wires or cables, in tiers. (TIA)

ducted skirting - A cable raceway with a removable cover made of either wood, plastic, or metal found on the perimeter of walls of a building. May have separate channels for power in telecommunications. See also raceway.

ductpic - Plastic insulated conductor cables designed for placement underground.

duct plug - A fitting capping the end of a duct, or fittings to surround cables within the duct, designed to provide a gas- and liquid-tight seal.

duplex - A simultaneous two-way independent transmission in both directions. See also half-duplex and full-duplex signaling.

duplex connector - See connector, duplex; optical fiber.

duplexer - A device that isolates the receiver from the transmitter while permitting them to share a common antenna.

duty cycle - The percentage of "on" time or operating time a device experiences.

dynamic power control (DPC) - The capability of raising and lowering a mobile's transmitting power in real time to help reduce interference.

dynamic range - A combination of the total pulse power of an OTDR laser source and the sensitivity of the associated sensor. Measurements are listed as a value reported in dB where larger values mean longer distance capability.

earth current - Alternating or direct current that flows in the earth whether momentary, intermittent, or continuous.

earth curvature - (earth bulge) The curvature of the Earth and its affect on lineof-sight communications links that are more than 10 km (6.2 mi) apart.

earth ground - An electrical connection to earth obtained by a grounding electrode system. See also approved ground and ground.

earthing - See grounded.

earthing electrode - See grounding electrode.

earth potential rise (EPR) - See ground potential rise.

earth resistance test - The testing of earth electrodes and the measurement of soil resistivity.

easement - A right acquired by one party to use land belonging to another party for a specific purpose. edge The point at which the enterprise network intersects with the Internet service provider network.

edge device - 1. A device designed to connect the enterprise network with an Internet service provider (ISP) network, generally owned by the ISP. 2. A device designed to transfer data between a local network (e.g., Ethernet or token ring) and an internetwork that uses a different technology (e.g., asynchronous transfer mode).

edge site - Generally, a small office connected to a network operation center or headquarters via an Internet service provider network. Also called a remote or branch site.

effective ground - Intentional connection to earth through a ground connection or connections of sufficiently low impedance (whose value is specified in suitable grounding/earthing/bonding standards) and having sufficient current-carrying capacity to prevent the buildup of voltages that may result in undue hazards to connected equipment or to persons. (NEC)

effective isotropic radiated power (EIRP) - The arithmetic product of the power supplied to an isotropic (ideal [imaginary] spherical omnidirectional) antenna and its gain.

effective radiated power (ERP) - The power supplied to an antenna multiplied by the antenna gain in a given direction.

egress - A point of exit from a building or property.

elastomeric - Characteristic of a material or substance allowing stretching and or flexibility, resembling rubber or elastic.

elastomeric firestop - A flexible firestopping material resembling rubber.

electrical closet - Floor-serving facility for housing electrical equipment, panel boards, and controls. (TIA)

electrical coupling - 1. The transfer of energy between two circuits due to electric field. This coupling can be represented by a capacitor. This effect also is called capacitive coupling. In telecommunications cables, this is due to the mutual capacitance of its conductors. 2. The transfer of energy between two or more electrically conducting bodies. This energy can be through a direct connection or an indirect connection (e.g., electromagnetic interference/radio frequency interference). Also called electric field coupling.

electrical distribution panel (EDP) - An assembly, mounted in or on a wall and accessible only from the front, consisting of enclosures, buses, and switches to control light, heat, or power circuits.

electrical drawing - Two-dimensional graphical representation of the electrical components of a construction project (e.g., power distribution, lighting).

electrical-magnetic coupling - The transfer of energy, through an indirect magnetic connection, between any two electrical conducting bodies. For differences, see harmonic coupling.

electrical metallic tubing (EMT) - Thinwail metal tubing that does not have threaded ends, which is widely used in electrical distribution systems and as a pathway for telecommunications cabling.

electrical noise - Unwanted voltage or current, or both, that appears in an electrical system. For given system characteristics, electrical noise may impair proper functioning.

electrical service equipment - That portion of the electrical power installation, the service enclosure or its equivalent, up to and including the point at which the supply authority makes connection. (TIA)

electric field strength - A vector quantity fully described when its magnitude and direction are given. Electric field is expressed in volts per meter, and the direction of the electric field at each point in space is that in which a positive electric charge placed at that point will move. See also voltage gradient.

electric latch retraction - Allows doors equipped with exit devices to be operated in push-pull (dogged) mode by electrically retracting the latch bolts.

electric lockset - An electrified version of a standard lockset that generally comes in two basic configurations. Available products incorporate an actuating solenoid that locks or unlocks a lockset, duplicating or replacing the function of a traditional mechanical key.

electric strike - An electrified locking element that replaces a traditional doors fixed strike with an electromechanical unit that upon application (fail secure) or removal (fail-safe) of power, a solenoid electrically activates the keeper, allowing a lock's latch bolt to pass.

electromagnetic compatibility (EMC) - The ability of the design and operation of equipment in a manner that makes them immune to certain amounts of electromagnetic interference, while keeping the interference generated by them within specific limits.

electromagnetic coupling - The ability of an electrical circuit to indirectly connect to another circuit through the magnetic field transfer of energy (electromagnetic interference) or radio frequency (radio frequency interference) energy transfer from one conductor to another.

electromagnetic disturbance - Any electromagnetic occurrence that may degrade the performance of a device, unit of equipment, or system. An electromagnetic disturbance may be noise, an unwanted signal, or a change in the propagation medium.

electromagnetic emission - The phenomenon by which electromagnetic energy emanates from a source. Emissions can be either radiated or conducted when coupled into a given disturbed circuit. Such emissions may be divided into two categories: intentionally emitted signals and unintentional electromagnetic emissions. See also emission.

electromagnetic environment - The electromagnetic field existing in a transmission medium.

electromagnetic field tester - Measures the presence of electromagnetic interference.

electromagnetic field (EMF) - The energy field radiating from a source and containing both electric and magnetic field components. An electric field is a field surrounding a charged object. A magnetic field is the field surrounding any current-carrying conductor.

electromagnetic immunity - The ability of a device, equipment, or system to perform without degradation in the presence of an electromagnetic disturbance.

electromagnetic induction - Current flow in telecommunications conductors produced by coupling of a magnetic field (e.g., by current in power lines, the cable shield, or other cable pairs).

electromagnetic interference - EMQ Radiated or conducted electromagnetic energy that has an undesirable effect on electronic equipment or signal transmissions. (TIA)

electromagnetic lock - An electric lock that uses an electromagnet to hold a door closed.

electromagnetic radiation - (EMR) Radiation made up of oscillating electric and magnetic fields and propagated with the speed of light. Includes gamma radiation, X rays, ultraviolet, visible, and infrared radiation, radar, and radio waves.

electromagnetic spectrum - The full range of electromagnetic emissions, which includes all light and radio waves.

electromagnetic susceptibility - The inability of a device, equipment, or system to resist an electromagnetic disturbance.

electromagnetic wave - A wave produced by the interaction of time-varying electric and magnetic fields.

electromotive force (EMF) - The maximum potential difference between two electrodes of a galvanic or voltaic cell, commonly referred to as voltage.

electronic access control - A system composed of computer software and hardware for managing access to identified spaces through the use of established security levels, issued credentials, and peripheral electronic hardware, including door contacts, request to exit devices, card readers, and electronic locking hardware.

Electronic Industries Alliance (EIA) - An alliance organized along specific electronic product and market lines, and, as a standards association, develops and publishes industry guidelines.

electronic serial number (ESN) - A unique 32-bit serial number permanently stored in the mobile station or cellular equipment by the manufacturer. The ESN is transmitted during the authentication process.

electronic switching system (ESS) - A digital electronic technology used for centralized voice systems.

electrostatic coupling - The induction of electrical charges in electrical conductors that may be the result of capacitive coupling from the electric field (e.g., of a nearby power line).

electrostatic discharge (ESD) - Electrical release of static electricity generated by interaction of dissimilar materials.

electrostatic field - Space in which there is electric stress produced by static electric charges.

electrostatic induction - Induced currents in electrical conductors as a result of the coupled voltage due to capacitive coupling (by electric field) of a riearby electric line.

elevation drawing - A two-dimensional graphical representation of a vertical plane (side view).

emergency power - A stand-alone secondary electrical supply source not dependent upon the primary electrical source. (TIA)

emission - The phenomenon by which electromagnetic energy emanates from a source. Emission can be either radiated or conducted. Such emissions may be divided into two categories: intentionally emitted signals and unintentional electromagnetic emissions.

emulation - The technique of modifying a device with hardware or software to make it operate in the same manner as another device. See also terminal emulation.

encapsulant - A permanent or removable filling compound for a splice enclosure to prevent water intrusion.

encapsulation - 1. A process that enables message transfer over dissimilar networks. It is used when messages initiated by network devices must be transported over an intermediate network using different protocols. The encapsulation process places messages into data frames compatible with the intermediate network without altering the message content. Upon arrival at the destination network, the reverse process is used to extract the original form of the message. 2. The process of installing permanent or removable filling compound. See also encapsulant.

enclosure - A case or housing for equipment, cable terminations, and cross-connect cabling. (TIA)

encoding - The process of writing data to a card. See also signal encoding

encroachment - The private use of another person's right-0f-way for an indefinite term, with or without permission, usually involving obstructions (man-made structures).

encroachment permit - A legal document (usually issued by a government agency) that gives the permit holder permission to install and maintain facilities over or under the property designated by the permit.

encryption - 1. A security mechanism that transforms readable data content into a seemingly random collection of characters, numbers, and/or symbols to provide confidentiality. 2. A modification of a bit stream to make it appear random and to control emissions (e.g., direct sequence spread spectrum).

encryption key - See key.

encumbrance - Any lien, claim, or liability attached to the land that affects or limits the fee simple title to property.

end cap - 1. The endplate of a splice enclosure specifically arranged for the cable(s) entering and exiting the enclosure. 2. Closure at the end of a surface raceway or series of modular furniture units.

end node - A device attached to a network for originating or receiving information on that network.

end-of-line resistor (EOLR) - Resistor that permits active monitoring of a two-wire circuit by using low-level circuit current to detect a short or break.

endothermic - Absorbing heat energy.

endplate - See end cap.

end user - The ultimate consumer of a delivered good or service.

energy management system (EMS) - A computerized monitoring and control system used to manage and provide operational efficiency for electrical power, heating, ventilating, and air-conditioning, and lighting control systems.

energy per bit/spectral noise density (EbINO) - A signal to noise ratio applicable to digital communication systems; measured at the input to the receiver; used to predict receiver performance (e.g., bit error rate).

engineered judgment - Decision by a professional for a slight variance.

engine generator - A unit that uses a fuelpowered engine to drive a rotary generator to produce electrical power.

entrance bridge - A terminal strip that is an optional component in a network interface device and is provided for the connection of auxiliary disconnect outlet cable. (TIA)

entrance facility (EF) - 1. An entrance to a building for both public and private network service cables (including wireless) including the entrance point at the building wall and continuing to the entrance room or space. (TIA) 2. A facility that provides all necessary mechanical and electrical services for the entry of telecommunications cables into a building and that complies with all relevant regulations. (ISO)

entrance point (EP) - The point of emergence for telecommunications cabling through an exterior wall, a floor, or from a conduit. (TIA)

entrance room or space - A space in which the joining of inter or intrabuilding backbone facilities takes place. (TIA)

equalizer - An electronic device that compensates for the selective frequency losses of the cable that feeds into it.

equalizing conductor - Typically used for the equalization of different ground (earth) points of a building to keep them at the same potential (zero volt).

equal level far-end crosstalk (ELFEXT) - Crosstalk measured at the opposite end from which the disturbing signal is transmitted, normalized by the attenuation contribution of the cable or cabling.

equipment cable - A cable or cable assembly used to connect equipment to horizontal or backbone cabling. (TIA)

equipment distribution area (EDA) - Space allocated for end equipment including computer systems and telecommunications equipment. These locations shall not serve the purposes of an entrance room, main distribution area, or horizontal distribution area.

equipment grounding conductor - The conductor used to connect the' noncurrent-carrying metal parts of equipment, raceways, and other enclosures to the system-grounded conductor, the grounding electrode conductor, or both at the service equipment.

equipment rack - Typically a vertical aluminum or steel support rack that holds equipment and cable terminations.

equipment room (ER) - An environmentally controlled centralized space for telecommunications equipment that usually houses a main or intermediate cross-connect. (TtA)

equivalent facilitation - Departures from particular technical and scoping requirements of this guideline by the use of other designs and technologies are permitted where the alternative designs and technologies used will provide equivalent or greater access to and usability of the facility.

error - Any unwanted change in the original contents of a transmission

error control - A process that verifies that a message is transferred successfully between devices.

errors and omissions (E80) - The failure to include or accurately define a requirement in a design document.

estimator - A person who evaluates a proposed scope of work for purposes of approximating labor and materials to plan or bid on proposed scope of work.

Ethernet ALAN - protocol using a logical bus structure and carrier sense multiple access with collision detection. Ethernet standards are formulated by the IEEE 802.3 committee and apply to Open Systems Interconnection Reference Model Layers 1 and 2.

Ethernet in the first mile (EFM) - The Institute of Electrical and Electronics Engineers 802.3ah project, Information Technology-Telecommunications and Information Exchange Between Systems-Local and Metropolitan Area Networks-Specific RequirementsPart 3: Carrier Sense Multiple Access with Collision Detection (CSMAlCD) Access Method and Physical Layer Specifications-Media Access Control Parameters, Physical Layers and Management Parameters for Subscriber Access Networks, to develop a standard Ethernet-based technology for linking subscribers to their telecommunications circuit providers.

European economic area (EEA) - An area composed of European Union, Iceland, Norway, and Liechtenstein.

European Radio Messaging System (ERMES) - A paging protocol defined by the European Telecommunications Standards Institute.

event - An occurrence at a controller (e.g., locking/unlocking a door, requesting to exit, forcing a door open) that generates a message stored in the controller.

event table - The results of some optical time domain reflectometers for optical fibers that list each event, its location, loss, and reflectance (if any).

existing facility evaluations - An investigation of an existing facility to help determine its suitability for adaptation to the owner's needs and goals, including functional, facility systems, structural, environmental, and accessibility evaluations. (CSI)

exothermic weld - A method of permanently bonding two metals together by a controlled chemical reaction releasing heat, resulting in a molecular bond. (TIA)

expansion joint - A joint between adjoining surfaces (e.g., concrete, conduit) arranged to permit expansion and contraction with changes in temperature.

exposed - Capable of being inadvertently touched or approached near than a safe distance by a person. It is applied to parts that are not suitably guarded, isolated, or insulated. (NEC)

exposed facilities - Any cable facilities subjected to such effects as lightning, power crosses, power induction, or differences in ground potential.

exposure monitor - A device worn by a cabling installer indicating the level of exposure to a hazardous substance.

extended service set (ESS) - A collection of wireless access points that are tied together by a wired backbone in a single collision domain, or by virtual LANs, to allow Layer 2 (Link layer) roaming.

extensible markup language (XML) - A specification developed by the W3C. XML is a pared-down version of standard generalized markup language, designed especially for Web documents. It allows designers to create their own customized tags, enabling the definition, transmission, vafidation, and interpretation of data between applications and between organizations. XML has been widely adopted for use in the integration of computiny systems with automation and control systems as the underlying language behind XML Web services.

extension arm - Metal or wood pole attachment for aerial cable to eliminate pull on an unguyed pole.

extranet - An interconnection of networks between organizations for the purpose of exchanging data. See also commerce server.

F connector - A 75-ohm radio frequency connector typically used in cable television and on entertainment devices for coaxial cable.

fabric - An interconnection scheme that enables communications between any two connected devices or networks through a series of interlinked switches.

fabrication tolerances - Establishes a statistical range of acceptability for properties of products before they are incorporated into the project. (CSI)

faceplate - A protective and/or decorative plate for an outlet.

facility code - The coded data in access control cards that identifies the location of the access control system.

fade bandwidth - The narrow bandwidth where fading is witnessed.

fade margin - A design allowance that provides for sufficient system gain or sensitivity to accommodate expected fading for the purpose of ensuring that the required quality of service is maintained.

fading - The variation in path loss between the transmitter at one station and its normal receiver at the following station.

failback - Restoration of normal operation from a failover.

fail latched - Provides a locking device that on loss of power will latch or remain latched but does not necessarily restrict movement from the secured side.

fail locked - An electric lock that requires power to unlock. Also called fail secure.

failover - The automatic transfer of control from a primary to a backup system as a strategy for fault tolerance.

fail-safe door - When the power fails at a door, the door automatically unlocks, allowing exit and entrance.

fail-safe lock - A lock that automatically unlocks a door upon loss of power. It takes power to lock a device of this type. A fail-safe lock is used for life safety applications. Also called power lock.

fail-secure door - When the power fails at a door, the door automatically locks and will not allow entrance but will continue to allow exit.

fail-secure lock - A device that automatically locks a door upon loss of power. It takes power to unlock this type of device. Also called power unlock.

fail unlocked - An electric lock that automatically unlocks with any power interruption. Also called fail-safe.

fallback - The ability of an access point to lower the transfer rate as the signal level from the mobile station drops below the level required to maintain a reliable connection.

false ceiling - See suspended ceiling. (TIA)

false event - A reading on an optical time domain reflectometer that is caused by the improper use of the test set or the test setup presents a false reading in the test results.

fanned - Separated cable conductors, strands, or pairs.

fan out - 1. Used to describe the physical preparation of wire pairs exiting the jacketed cable to facilitate placement and termination in a splice or connecting block. 2. A device used to enable termination of optical fiber strands.

Faraday's law - The physical law that a changing magnetic field produces an associated electric field.

far-end crosstalk (FEXT) loss - A measure of the unwanted signal coupling from a transmitter at the near end into another pair measured at the far end, and relative to the transmitted signal level. Also called input/output far-end crosstalk loss. (TIA)

fault management - The detection, isolation, and correction of hardware or software conditions that disrupt network operations.

fault tolerance - The ability of a system to continue operations after the failure of one or more components or communications paths.

fault voltage (current) - See foreign voltage (current).

FC connector - See fiber connector.

feedback - An unwanted oscillation or tone that quickly increases in audible level.

feeder duct - See header duct and trench duct.

feed horn - A device that concentrates radio frequency energy into a waveguide, antenna radiator, or antenna reflector.

ferroresonance - The resonance of iron molecules due to the application of a magnetic field that produces a magnetic flux on the iron structure. This is the principle of operation of transformers.

ferroresonant transformer - A device that gives regulated alternating current (ac) voltages, capable of acting as a stepup or step-down voltage transformer and as an ac voltage regulator.

ferrule (optical fiber) - The alignment sleeve portion of an optical connector used to protect and align the stripped optical fiber.

fiber - See optical fiber.

fiber connector (FC) - A type of optical fiber connector identifiable by its round, threaded connector body. The threaded design provides for a secure optical fiber connection. May be of metal or composite material.

fiber distributed data interface (FDDI) - A fault-tolerant token-passing network protocol based on single or dual optical fiber rings.

fiber distribution hub (FDH) - Network equipment required to house passive components and to terminate in-building optical fiber distribution cables.

fiber distribution terminal (FDT) - Network equipment (passive) required to terminate fiber jumpers to each line unit.

fiber distribution unit - An administrative housing used to terminate fiber cables and connectors for the purpose of interconnections and cross-connection.

fiber optic - See optical fiber.

fiber optic cable - See optical fiber cable.

fiber optic flashlight - See optical fiber flashlight.

fiber optics - A communications system that uses optical fiber as its media.

fiber span - A length of optical fiber cable between poles or maintenance holes.

fiber strand identifier - A clamp-on testing unit for optical fiber that places a microbend into the cable to detect light escaping from the fiber.

fiber to the curb (FTTC) - In an FTTC outside plant residential cabling system, singlemode optical fiber is extended to the pedestal, which is at the curb near the home. Depending on the termination point, the system can be referred to as an FTTx system, where "x" represents the home, business, premises, or curb. The drop from the curb to the home is typically balanced twisted-pair, although if FTTC is used to provide video, a dual drop cable containing both balanced twisted-pair and coax may be cost effective in comparison with the cost of the electronics needed to multiplex and demultiplex telephony and video bandwidth signals over a balanced twisted-pair drop alone.

fiber to the home (FTTH) - A technology that provides voice, data, and video services from the telephone company's branch office to local customers over an all optical fiber link.

fiber to the premises (FTTP) - See fiber to the curb (FTTC).

Fibre Channel - A high-speed, point-to-point network protocol commonly associated with storage area network technologies.

field engineering - Consists of taking the measurements, facility placement, and layout from the field observations. Field engineering includes site surveying and layout.

field observation reports - Site visits are documented in the form of a field observation report, with any observed deficiencies clearly noted, to keep the owner informed of construction progress and events taking place on the construction site. (CSI)

field order (FO) - Allows the engineer to authorize or order minor variations in the work when such changes do not involve a change in contract price or contract time. These orders must be in writing, but do not require an executed change order or the owner's signature. (CSI)

fill - 1. A sequence of added bits used to meet timing, sizing, or spacing requirements in and between messages. 2. Use of material (or material used) to equalize or raise earth topography to a certain elevation.

filled cable - A cable that contains waterblocking gel material inside the sheath to prevent the penetration of moisture into the cable.

fill ratio - The ratio of actual space occupied to potential total space by any material that fills a container. Typically expressed as a percentage of the total cross-sectional space. In the case of round telecommunications cables, a conduit, for example, may become completely full of cable with a 60 percent fill ratio because round cables filling a round space (e.g., conduit) does not allow for 100 percent full. Water, for instance, may completely fill a conduit with a 100 percent fill ratio.

filter - 1. A process or device that examines all incoming traffic for specific characteristics (e.g., source address, destination address, protocol, virus) and determines whether to accept, forward, or discard that traffic based on the established criteria. 2. A device that selectively sorts and passes through a desired range of signals (e.g., noise suppression).

filtering - A process that examines all incoming data for specific characteristics (e.g., source address, destination address, protocol) and determines whether to accept, forward, or discard that traffic based on the established criteria. See also filter.

filter mask - Protective breathing apparatus worn whenever harmful dust, gas, smoke, chemical vapor, or some other pollutant is present at the work site.

final acceptance - Final acceptance of the work is indicated by issuance of final payment. Final payment is recommended by the architect or engineer only after all project closeout procedures have been completed. (CSI)

fingerprint reader - A biometric reader that identifies a person based on the person's fingerprint pattern.

finish grade - The top surface of lawns, walks, or other improved surfaces after the completion of grading operations.

fire alarm (FA) - A system that provides a reasonable level of safety by reducing the probability of injury and loss of life from fire, smoke, and heat in buildings by providing detection, suppression, and notification functions.

fire alarm code - A code that specifies when a fire alarm system is required.

fire alarm control panel (FACP) - A system-level controller that initiates sequences of operation for fire detection, suppression, and notification functions.

fire alarm standard - A standard that prescribes such requirements as the spacing and placing requirements of fire detection and alarm equipment. This addresses how a fire alarm system is to be installed, tested, inspected, maintained, and monitored.

fire break - A fire-rated material, device, or assembly of parts installed along a cable, other than at a cable penetration of a firerated barrier, to prevent the spread of fire along a cable. (TIA)

fireproof - A property of a material (e.g., masonry, block, brick, concrete, gypsum board) that does not support combustion even under accelerated conditions. No material is entirely fireproof.

fire-rated door - A door assembled of various materials and types of construction used in wall openings to retard the passage of fire. These doors are rated in hours or fractions of hours.

fire rating system - See fire resistance rating.

fire resistance - A property of a material or assembly of materials that can withstand combustion and delay the passage of flame for some known period of time.

fire resistance rating - The time in hours, or fraction thereof, that a material or assembly of materials will withstand the passage of flame and the transmission of heat when exposed to fire under specified conditions of test and performance criteria. (TIA)

fire retardant (FR) - Any substance added to delay the start of fire ignition or to slow the spread of flame by the burning material.

fire shield - A fire-rated material, device, or assembly of parts between pathways (e.g., between two parallel cable trays or between layers in vertically stacked trays) to prevent propagation of flames from one pathway to an adjacent pathway. (TIA)

firestop - A fire-rated material, device, or assembly of parts installed in a penetration of a fire-rated barrier. (TIA)

firestop seal - See firestop system. (TIA)

firestop system - A specific construction consisting of the material(s) (firestop penetration seals) that fill the opening in the wall or floor assembly, and around and between any items that penetrate the wall or floor (e.g., cables, cable trays, conduit, ducts, pipes), and any termination devices (e.g., electrical outlet boxes) along with their means of support.

firewall - 1. A continuous barrier used to prevent fire spreading from one fire zone or area to another. 2. One or more security mechanisms (hardware and/or software) designed to prevent, detect, suppress, and/or contain unauthorized access to a network.

Firewire - IEEE 1394 serial bus protocol for high-speed communications.

fire zone - A contained area completely enclosed by fire-resistant rated walls, floors, and ceilings

first generation (1G) mobile telephony - Based on analog technology. 1G systems have been phased out and replaced with faster, more reliable digital cellular systems.

fish tape - A tool or device made of steel or fiberglass that can be pushed into a conduit to assist in installing a pull line or to pull cable(s).

fixed device - Any low-voltage device permanently affixed to a surface for purposes of security, fire detection or other control, data, or entertainment applications. (TIA)

flash cut - A process of migrating from an existing system to another where all circuits are cutover at once. See also cutover and hot cut.

flashing - Pieces of sheet metal or the like used to cover and protect certain joints and angles.

flat network - A network that consists of a single broadcast domain. See also broadcast domain.

FLEXT - Synchronous, one-way, time-slot, paging protocol.

flexible conduit - A raceway of circular cross-section that is bendable without the use of tools.

flex life - A qualification of the number of times a cable may be bent before breaking.

float current - The current that is drawn by a battery when it is being kept in a fully charged state. This current will be determined by the float voltage. See also float voltage.

float voltage - The voltage at which a battery is maintained (floated) in order to keep it in a fully charged state. See also float current.

flooding - The process used by switches/ bridges and routers to direct a message to all outgoing ports, with the exception of the port or interface on which the traffic was received.

floor distributor (FD) - The distributor used to connect horizontal cable and cabling subsystems or equipment. International equivalent term for horizontal cross-connect.

floor plan - 1. A scaled diagram or plan of a building floor or other structure. 2. Plan showing the layout of a building floor.

floor-serving terminal - The space where backbone and auxiliary disconnect coaxial cables terminate to support a single level of living units.

floor slab - 1. That part of a reinforced concrete floor, which is carried on beams below. (TIA) 2. A concrete mat poured on subgrade serving as a floor rather than as a structural member.

flow control - A mechanism used to manage the frame exchange rate between source and destination devices that prevents the source from overwhelming the destination.

foil shield - A thin plastic and metal laminated tape wrapped around the cable conductors and acting as a shield against electromagnetic interference and preventing emission of electromagnetic energy.

foil twisted-pair (FTP) cable - See screened twisted-pair cable.

foiled twisted quad (FTQ) cable - A cable with two individual groups of four twisted conductors surrounded by an overall foil shield.

foldback splicing - Process of folding back conductors in a splice for future maintenance or rearrangements.

footprint - The area where a piece of equipment or furniture rests on the floor with its moving parts in a closed position.

foreign voltage (current) - Any unwanted voltage (current) imposed on a system that is not supplied from the central office or from telephone equipment or from within the system itself. Also called fault voltage (current).

form and dress cable - Line up cables side-by-side, shape into sweeping arcs, and join cable into bundles with tie wrap, or other means, to hold bundles together.

form factor - In computers, the size, configuration, or physical arrangement of a device, in physical terms rather than capability.

forwarding - The transferring of a message to another network by an internetworking device. See also filtering.

forwarding logic - The set of rules used by a switch to process the messages received from LAN devices.

forward packet data channel (F-PDCH) - The cdma2000 1xEV-DV data channel on the forward link. forward proxy See Internet acceleration.

forward voice channel (FVC) - Works in pair with the reverse voice channel for a subscriber call. (Nortel)

fragment-free switching - See modified cut-through.

frame A - data unit created at Layer 2 of the Open Systems Interconnection Reference Model. It contains the data and control information necessary to transfer a message from one device to another on the same network.

frame check sequence (FCS) - The product of an error-detecting code normally inserted as the final field in a block of transmitted data.

Frame Relay (FR) - A network protocol designed to transport messages rapidly overextended distances via a mesh network, using virtual circuits and switches. A high-performance derivative of X.25.

frame synchronization (FS) - A 32-bit post office code standardization advisory group paging code used to identify the beginning of each message batch.

franchise - A right-of-way granted for placement of outside plant facilities within the domain of public or private property.

free space loss - The signal loss that occurs between two isotropic antennas in free space, unaffected by blocking, refraction, diffraction, or absorption.

free space optics (FSO) - Low power laser beam used for outdoor point-to-point high rate, protocol independent, transmission.

frequency (freq) - The number of cycles that a periodic signal completes in a given time; if the unit of time is one second, the frequency is stated in hertz (Hz). One Hz is equal to one cycle per second.

frequency band - A range of communications frequencies.

frequency converter - Integrated component assemblies used for converting signals into various frequency ranges for further processing.

frequency deviation - The change of a carrier frequency as the result of modulation measured in percent of deviation.

frequency-division multiplexing (FDM) - A system that allows the transmission of more than one signal over a common path, by assigning each signal a different frequency band.

frequency-hopping spread spectrum (FHSS) - A modulation technique that employs rapid changing of the transmission frequency in a predetermined, pseudorandom pattern. Communication is accomplished by synchronizing the transmitter and receiver.

frequency modulation (FM) - Modulation in which the instantaneous frequency of a sine wave carrier is caused to depart from the center frequency by an amount proportional to the instantaneous value of the modulating signal. In FM, the center frequency is called the carrier frequency.

Fresnel reflection - Reflection of a portion of incident light at a discrete interface between two media having different refractive indices or media discontinuity.

Fresnel zone - The circular zone about the direct path between an electromagnetic wave transmitter and receiver in an unbounded transmission medium free of radiation sources.

frost line - The deepest level below grade to which frost penetrates in a particular geographic area. Usually specified in 50year increments.

full-duplex signaling - The transmission of data in two directions simultaneously. See also dual-duplex signaling, half-duplex signaling, and simplex signaling,

functional design process - A network design process where the designer begins by examining the types of applications and services that are to be supported by the network. Also called top-down design. Contrast with physical design process.

furcating harness - An assembly used to increase the effective outer diameter of strands within an optical fiber cable to enable connector termination, typically provided in either 6- or 12-strand configurations. Also called a fan out.

furcation - The process of covering a 250 micron coated optical fiber with a 900 micron buffer tube to facilitate field connectorization.

furcation tubing - Flexible tubes used to increase the effective outer diameter of coated optical fiber strands (typically from 250 micron to 900 micron) to enable connector termination and provide physical protection of the coated strands.

fuse - An overcurrent protective device with a circuit-opening fusible element that is severed (open) when heated by the passage of an overcurrent.

fuse cable link - A length of cable that is two gauges smaller than the conductors of the cable being protected and at least 0.6 m (2 ft) long. Fuse cable is inserted in the plant and intended to open on excessive foreign power currents.

fuse link - See fuse cable link.

fusing - 1. The process of joining optical fibers together by fusion. 2. The process of joining materials through a chemical or heating process.

fusion splice - A permanent joint accomplished by applying localized heat sufficient to fuse the ends of two optical fibers together, forming a continuous single optical fiber.

gain - The increase in output current, voltage, or power relative to input current, voltage, or power, respectively. Gain is usually expressed in dB. Gantt chart - A simple chart that diagrams a project schedule. gap distance - The distance between optical fiber ends. gas tube protector - An overvoltage protector featuring metallic electrodes that discharge in a gas atmosphere within a glass or ceramic envelope. This type of protector does not require replacement each time it discharges. gateway - An internetworking service used to connect dissimilar applications running on different networks with different communications protocols. Gateways normally operate at one or more of the top four layers of the Open Systems Interconnection Reference Model. See also portal and wireless LAN gateway. Gaussian noise - In electrical conductors, the noise resulting from molecular vibration. This background noise increases logarithmically with temperature. general conditions - Any of a number of standards or code documents published that are applicable to the project delivery method. Gigabit Ethernet (GbE) - A LAN protocol with a data transfer rate of 1000 Mbls (1 Gb/s). gigabit per second (Gbls) - A transmission rate denoting one billion bits per second. gigahertz (GHz) - A unit of frequency denoting one billion cycles per second. See also hertz (Hz). glass fiber - See optical fiber. global unlock - An input that, when activated, generates a signal that unlocks doors in the access control systems. gopher pole - A telescoping pole for placing or pulling cable above suspended ceilings or limited access areas. Grade 1 residential telecommunications cabling - Cabling that provides a generic cabling system that meets the minimum requirements for telecommunications services (e.g., telephone, satellite, community antenna television, data services). Grade 2 residential telecommunications cabling - Cabling that provides a generic cabling system that meets the requirements for current needs as well as for developing basic, advanced, and multimedia telecommunications services. grade of service (GoS) - With respect to the percentage of blocked calls to the completed calls, defined as calls blocked. (Nortel) graded index profile - The refractive index profile of an optical fiber. See gradedindex fiber. graded-index fiber - An optical fiber design in which the refractive index decreases continuously from the center of the core to the outside of the core. grommet - Generally a rubber insulator used to protect a wire passing through an aperture. See also bushing. ground - A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of earth. (TIA) See also approved ground and earth ground. grounded - Connected to earth or to some conducting body that serves in place of the earth. grounded conductor - A system or circuit conductor that is intentionally grounded. ground enhancement material - Any material used to enhance the soil for a low resistance to ground. ground fault circuit interrupter (GFCI) - A device intended for the protection of personnel that functions to deenergize a circuit or portion thereof, within an established period of time, when a current to ground exceeds the values established for a Class A device. (NEC) ground fault - An undesirable connection to ground. ground grid - An extensive system of bare conductors, buried below the surface of the earth, intended to provide a low-resistance connection to earth and to equalize the potential within the area covered. (TIA) grounding - See grounded. grounding bushing - A fitting for attaching a ground wire to a conduit. grounding conductor - A conductor used to connect the grounding electrode to the building's main grounding busbar. (TIA) grounding electrode - 1. A conductor, usually a rod, pipe, or plate (or group of conductors), in direct contact with the earth for the purpose of providing a lowimpedance connection to the earth. (TIA) 2. A device that establishes an electrical connection to the earth. (NEC) grounding electrode conductor (GEC) - The conductor used to connect the grounding electrode to either the equipment grounding conductor, or to the grounded conductor of the circuit at the service equipment, or at the source of a separately derived system. (TIA) grounding electrode system - One or more grounding electrodes bonded to form a single reliable ground for a structure. See Codes, Standards, and Regulations. grounding equalizer (GE) - A conductor that interconnects elements of the telecommunications grounding infrastructure (formerly telecommunications bonding backbone interconnecting bonding conductor. grounding grid - See grounding mat grounding mat - An extensive system of bare conductors, buried below the surface of the earth, intended to provide a low-resistance connection to earth and to equalize the potential within the area covered. (TIA) grounding system - A system of hardware and wiring that provides an electrical path from a specified location to an earth ground point. grounding terminal - A suitable bar, bus, terminal strip, or binding post terminal where grounding and bonding conductors can be connected. ground loop - Interference in electrical communication links due to the ground at each end being at different potentials. ground plane - A system of conductors placed beneath an elevated antenna as a near field reflective point serving as an earth ground. ground potential - The zero reference level used to apply and measure voltages in a system. ground potential rise (GPR) - A voltage difference between a grounding electrode system and the earth return currents produced by a lightning strike or a powerfault current. ground-reflected wave - The portion of a wave that reaches a receiving antenna after it has reflected off the Earth's surface. ground resistivity - The measured direct current resistance of a volume of earth. ground ring - A ground ring encircling the building or structure, in direct contact with the earth at a depth below earth surface not less than 0.76 m (2.5 ft), consisting of at least 6 m (20 ft) of bare conductor not smaller than No. 2. (NEC) ground rod array - Consists of two or more ground rod assemblies, bonded together, separated by a distance equal or greater than the length of the ground rod assembly. ground wave - A low-frequency radio wave that bends along the earth's surface rather than traveling through the atmosphere. ground wire - See bonding conductor and bonding conductor for telecommunications. groupware - A network software application designed to enhance administrative communications (e.g., e-mail, scheduling, coordination, collaboration) among users in an organization. guaranteed maximum price (GMP) - Bidders may be required to state a GMP that is not to be exceeded. This allows the owner an understanding of the absolute maximum cost of the project before start of construction. guard band - In analog signals, guard bands are small bands of unused frequencies that are allocated as buffers between data carrying channels: Guard bands provide a buffer against interference from adjacent channels due to signal drift. guy - A steel stranded wire used to provide counter tension to the pole opposite that of the installed cable pull tension to keep the pole upright. guy rod end - A single, double, or triple eye at the end of a guy rod for the attachment of the guy wire to the connect point above the ground anchor.

half-duplex signaling - A bidirectional signaling method in which data transfer can take place in either direction, but in only one direction at a time. Contrast with dualduplex signaling, full-duplex signaling, and simplex signaling.

half-tap - Splicing of a cable or individual pairs where the through cable/conductor is not cut until the cutover takes place. This is a "hot cut" penetration step.

hand geometry - A biometric reader that verifies a person's identity using the variations in hand size, finger length, and finger thickness.

hand trace - The act of physically hand tracing a cable, patch cord, jumper, or crossconnect from one known point to another known point to determine its path.

handhole (HH) - A structure similar to a small maintenance hole in which cable can be pulled, but not large ertough for a person to fully enter to perform work.

handoff - The process that occurs when a mobile user moves from one cell (thereby terminating communications) to another cell (thereby initiating communications) in a cellular network. The handoff is accomplished without disruption of the exiting connection.

handover - See handoff.

handshaking - A connection-oriented protocol. The process whereby verification is established before controlled data is sent to a remote system. When handshaking is successful, the systems establish connection.

hardened equipment - Outdoor housed equipment or apparatus designed to withstand varying temperature, dust, and seismic conditions.

hard-line trunk - A rigid coaxial cable, typically used for backbone cabling. (TIA)

hard-sheath cable - A cable or wire contained within a continuous inner or outer metallic sheath. (TIA)

hardware address - See device address and medium access control address.

hard-wire system - A connection in which a device is either connected directly to the wires within a cable by screw lugs or a splice.

harmonic - A frequency that is a whole number multiple of the fundamental frequency.

harmonic coupling - Used to describe the transfer of electrical energy from one signal into another signal in a different media through an indirect connection (usually electromagnetic interference). For the transfer to work, it must be a divisible multiple of the original signal's fundamental frequency. Any other energy transfer would be noise surrounding the signal. For differences, see electrical-magnetic coupling.

harmonic distortion - The presence of additional undesirable sinusoidal components at frequencies that are integer multiples of an original sinusoidal frequency.

headend - The equipment located at the start of a coaxial cable distribution system where the signals are processed and combined prior to distribution.

headend equipment - The main active components of a distributed antenna system (DAS). Headend equipment provides the interfaces for the donor services (i.e., those to be retransmitted by the DAS) and the interfaces to the backend equipment to facilitate distribution of radio frequency signals to the coverage areas on other floors or in other buildings on a campus.

header - The initial part of a message, typically containing identification and control information.

header duct (trench duct, feeder duct) - A raceway of rectangular cross-section placed within the floor to tie distribution duct(s) or cell(s) to the telecommunications room. (TIA)

heartbeat - The signals issued periodically by a clustered device to indicate that it is functioning normally.

heat coil - A device that grounds a conductor when the conductor's current time limits are exceeded.

heat shrink tubing - Rubber (or similar material) tubing that shrinks upon the application of heat. Used to insulate splices, connectors, or to create weather or environmental protection to a connection.

henry (H) - The unit used to measure inductance of magnetic fields.

hermaphroditic connector - A connector that is neither male nor female.

hertz (Hz) - A unit of frequency equal to one cycle per second.

heterodyning - The technology used to generate new frequencies by mixing two or more signals in a nonlinear device (e.g., a vacuum tube, transistor, diode mixer).

hidden node (HN) - An instance where two or more nodes in a wireless LAN are within transmission range of the same access point, but not within transmission range of each other.

hierarchical star topology - An extension of the star topology using a central hub connecting two or more middle layer hubs.

hierarchical topology - A topology that links devices or networks using a series of levels, similar to an organizational chart.

high pair-count cable - A cable where balanced twisted-pair conductors are bundled into sets of 25 pairs.

high-rate direct sequence spread spectrum (HRIDSSS) - A form of wireless signaling similar to DSSS, but employing a more advanced coding scheme to enable higher data rates.

high-speed downlink packet access (HSDPA) - A third generation mobile telephony digital cellular standard based on the evolution of wideband code division multiple access technologies.

home automation - The interoperation of devices and subsystems in the home.

home run - A pathway or cable between two locations without a splice or intermediate termination points in between.

horizontal cable - Distribution media that connect the telecommunications outlet/ connector at the work area and the first piece of connecting hardware in the horizontal cross-connect (floor distributor).

horizontal connection point - A location for connections between horizontal cables that extend from building pathways and horizontal cables that extend to building automation systems devices and equipment. (TIA)

horizontal consolidation point/telecommunications outlet cable - A segment of horizontal cable between the consolidation point connector and the telecommunications outlet/connector. This cable is intended to be easily moved for modular office rearrangement. Also known as horizontal CP-TO cable.

horizontal cross-connect (HC) [floor distributor (FD)]) - A group of connectors (e.g., patch panel, punch-down block) that allows equipment and backbone cabling to be cross-connected with patch cords or jumpers. Floor distributor is the international equivalent term for horizontal cross-connect.

horizontal directional drilling - A method for placing underground facilities that uses a directed horizontal auger or drill to establish the path, place casings or cables, and minimize restoration costs associated with plowing or trenching.

horizontal HC-CP cable - The segment of horizontal cable permanently installed between the horizontal cross-connect (HC) and the consolidation point (CP) connector.

host - 1. In the Internet environment, the term used to describe any network-attached device that provides application-level services. 2. A generic term used to describe mainframes and minicomputers.

host computer - The central controlling computer on which access control software runs.

host identification (hostid) - Part of an IP network address. It identifies a device within a broadcast domain. See also network identification (netid).

hot cut - A cutover where the active cables are unplugged from the old system and plugged into the new system. See also cutover and flash cut.

hot red light - A low-intensity laser.

hub - A network device that provides a centralized point for LAN communications, media connections, and management activities of a physical star topology cabling system.

hybrid cable - An assembly of two or more cables, of the same or different types or categories, covered by one overall sheath. (TIA) Contrast with bundled cable.

hybrid coupler - A component used to combine two wireless bands to a single antenna feed or distribution cable.

hybrid optical fiber cable - An optical fiber cable containing two or more fiber types (e.g., multimode and singlemode). (TIA)

ice bridge - The horizontal steel structure installed to support antenna cables running between a communications tower and shelter or cabinet housing wireless equipment. So named because the structure also shields the cables form ice that may fall from towers located in colder climates.

ice load - The weight factor calculated from the potential amount of ice that can build up on outside plant structures from storm conditions.

identifier (ID) - An item of information that links a specific element of the telecommunications infrastructure with its corresponding record. (TIA)

illuminator - A device that concentrates radio frequency energy at the focal point of a satellite dish. Also called a feed horn.

image rejection - The discarding of signal images by a receiver. Such images are produced due to mixing in the intermediate frequency section of the receiver, resulting in desired signals and undesired signal images.

imaging - The technologies associated with the conversion of documents into digital format,

immunity - The ability of a device, equipment, or system to perform without degradation in the presence of an electromagnetic disturbance.

impedance - The total opposition (resistance and reactance [capacitance and inductance]) that a circuit, cable, or component offers to the flow of alternating current at a given frequency. It is measured in ohms.

impedance discontinuity - An abrupt change in a cable's characteristic impedance. Impedance discontinuities can be caused by faulty connections, mismatched cable types, and untwisted sections on twisted-pair cable.

impedance match - A condition whereby the impedance of a particular circuit, cable or component is the same as the impedance of the circuit, cable or device to which it is connected.

impulse noise - Discrete noise spikes having random amplitude and spectral content.

incidental radiators - A device that generates radio frequency energy during operations although it has not been intentionally designed to do so.

independent basic service set (IBSS) - A group of stations in a wireless LAN that communicate directly with each other (without the use of a central access point). This type of network is also known as an ad-hoc network.

index of refraction (IOR) - The ratio of the velocity of light in a vacuum to the velocity of a signal in a given material. Also called refractive index.

index sheet - A part of the drawing set, maintained by the architect and providing general information, including the site address, owner's name, and architect's name.

index-matching gel - A material used in optical fiber connections or splices that has a refractive index close to that of the optical fiber core; used to reduce reflections from the residual air gap.

inductance - A condition that opposes the flow of current while causing a voltage phase shift in +90 degrees.

induction - Phenomenon of a voltage, magnetic field or electrostatic charge being produced in an object from the source of such fields.

inductive amplifier - Test device used to detect a signal placed on a cable for the purpose of tracing and identification. Also called a wand or probe.

inductive coordination - The cooperative effort of telecommunications and power company personnel in the engineering and application of measures and devices to ensure compatibility of operation between both systems for noise reduction and protection.

inductive coupling - The transfer of electromagnetic energy from one circuit to another.

industrial, scientific, and medical (ISM) - Unlicensed frequency band in the 2.4 GHz range.

industry negative file (INF) - A database consisting of fraudulently created mobile identification number/electronic serial number used to screen false cellular access.

information transport systems (ITS) - industry Pathways, spaces, cabling systems, wireless systems, and infrastructure that support the transportation of data and data signaling between communication, data processing, data display, or information gathering devices.

informational submittals - Document information the architect or engineer requires to verify performance and quality control of project components, but do not require approval. They are also used as verification and certification that the installed work or portion of the work meets the specified requirements. (CSI) infrared (IR) The electromagnetic spectrum having wavelengths between 750 nm and 1 mm (7.5o10-' m - 1. 10-3 m) or between 30 and 40,000 microinches (3o10-$ in - 4o10-2 in).

infrared conversion card - Allows a cabling installer to visually detect an infrared signal when that signal is directed at the card's phosphorus material.

infrastructure (telecommunications) - A collection of those telecommunications components, excluding equipment, that together provides the basic support for the distribution of all information within a building or campus. (TIA)

ingress - 1. An electrical characteristic associated with externally generated noise induced into cable facilities. 2. A point of entry for a building or property.

initiating device circuit (IDC) - A circuit to which automatic or manual initiating devices are connected where the signal received does not identify the individual device operated.

in-line splice - A splice in which cable enters one end cap and, after splicing the cable, exits the other end cap of the closure.

innerduct - A nonmetallic raceway, usually circular, placed within a larger pathway. (TIA)

input impedance - The ratio of the voltage at the sending end of the line to the current in the line at the sending end.

inrush (amperes) - The current that a device requires during its initial power-up.

insert - An opening into the distribution duct or cell from which wires or cables emerge. (TIA) See also insert, afterset and insert, preset.

insert afterset - An insert installed after the installation of the concrete floor slab or other flooring material. (TIA) See also insert; contrast with insert, preset.

insert, preset - An insert installed prior to the installation of the concrete floor stab or other flooring material. (TIA) See also insert; contrast with insert, afterset.

insertion card - A card that must be inserted into a card reader for the reader to retrieve the information stored on the card.

insertion loss deviation - The difference between the actual insertion loss as measured on a permanent link or channel and the insertion loss as determined by adding the component losses. (TIA)

insertion loss - The signal loss resulting from the insertion of a component, or link, or channel, between a transmitter and receiver (often referred to as attenuation). (TIA) See also attenuation.

instant messaging - Text-only real-time conferencing. Also called chat.

insulating gap - A capacitor installed on the field side of an insulating joint.

insulating joint - An opening in a cable sheath or down guy where continuity is deliberately interrupted to prevent the flow of currents.

insulation - The dielectric material that physically separates wires and prevents conduction between them.

insulation displacement contact (IDC) - A type of wire termination in which the insulation that is surrounding a conductor is displaced at the connection point without physically stripping the insulation from the conductor and consequently makes a gas-tight connection to the conductor.

integrated digital enhanced network (iDEN°) - A wireless technology that provides digital cellular telephone, two-way radio, alphanumeric pager, and data/fax modem services in a single network.

integrated services digital network (ISDN) - A fully digital communications facility designed to provide transparent endto-end transmission of voice, data, audio/ video, and still images across the public switched telephone network. Different versions exist for North America and Europe.

integration - The seamless gathering of many similar and dissimilar systems as if they were one system. In relation to electronic safety and security, integration may involve the interconnection or convergence of components of these systems as well as other building, vehicle, or communications systems for purposes of data collection, monitoring, management, and control. See also convergence.

integrity services - Network processes that provide the assurance that messages are authentic and unaltered.

intelligent device (ID) - Addressable device used to monitor and control functions in a building automation system network.

intelligibility - For voice communications, the capability of being understood by the intended audience. Intelligibility does not imply the recognition of a particular voice. It cannot be measured with instrumentation but may be electronically simulated and measured utilizing an indexing method.

intentional radiator - A device designed to generate and emit radio frequency energy during operations using radiation or induction.

inter-access point protocol (IAPP) - A protocol developed by the IEEE to enable interoperability between access points manufactured by different vendors. Adopted as IEEE 802.11f in 2003.

interbuilding (campus) backbone - A backbone network providing communications between more than one building.

interbuilding backbone cable - 1. Cable that runs between buildings in a campus environment. 2. Outside plant cabling.

interbuilding backbone cable interconnection - A connection scheme that employs connecting hardware for the direct connection of a cable to another cable without a patch cord or jumper, or single-port equipment connections to horizontal or backbone cabling.

interbuilding backbone pathway - Provides the means to connect main terminal spaces in different buildings.

interbuilding backbone - A pathway and/or cable facility from the entrance room/space provided for interconnecting to other buildings, as in a campus environment.

intercom/paging system - A communications device used for either one-way or two-way voice broadcasts.

interconnect - See interconnection

interconnection - 1. A connection scheme that employs connecting hardware for the direct connection of a cable to another cable without a patch cord or jumper. 2. A type of connection in which singleport equipment connections (e.g., 4-pair and optical fiber connectors) attach to horizontal or backbone cabling by means of patch cord or jumper.

interface - 1. A shared boundary. A physical point of demarcation between two devices or systems where electrical signals, connectors, and timing are defined. 2. The procedures, protocols, and codes that allow two devices to interact for the purpose of exchanging information.

interference - Undesirable signals on a device, equipment, or system. See also electromagnetic interference.

interlock - A system of multiple doors that control interaction. No door can be unlocked unless all other doors are secure and locked. Also known as light or air trap, mantrap, and sally port.

intermateability - See interoperability.

intermediate cross-connect (IC) [building distributor (BD)] - The connection point between a backbone cable that extends from the main cross-connect (campus distributor [first-level backbone]) and the backbone cable from the horizontal cross-connect (floor distributor [second-level backbone]). Building distributor is the international equivalent term for intermediate cross-connect.

intermediate distribution frame (IDF) - Refer to horizontal cross-connect (floor distributor) and intermediate cross-connect (building distributor).

intermediate frequency (IF) - The frequency to which a carrier frequency is shifted as an intermediate step in signal transmission or reception.

intermediate network - A network used to connect two or more networks. See also internetwork.

intermittent duty solenoid - A currentcarrying coil of wire that acts like a magnet when a current passes through it that is designed to be energized for short periods of time. Continuous operation maydamage an intermittent duty solenoid.

intermodulation interference (IMI) Also known as intermod. - Spurious signals that disrupt wireless communication and are the result of two or more strong signals passing through a nonlinear device and multiplying by each other. Most commonly, intermod is generated within a receiver's amplifying stages, especially when the receiving antenna is located near one or more powerful transmitters. Intermodulation products also can be produced in a transmitter when the signal from one transmitter unintentionally enters into another transmitter. Poor cable connections or connections between dissimilar metals can be a source of intermod.

Internet acceleration - A term used to describe a content acceleration appliance that is used to cache content requested by local users at a site. Normally such content is retrieved from remote servers over telecommunications circuits. Also called forward proxy. See also Web site acceleration.

Internet access management - See surf control.

Internet protocol (IP) - The Open Systems Interconnection Reference Model Layer 3 (Network layer) protocol most commonly used for internetworking. Required for communications over the Internet.

Internet protocol (IP) address - The Open Systems Interconnection Reference Model Layer 3 (Network layer) address assigned to devices using the IP. Also called an Internet address.

Internet protocol security (IPsec) - A security protocol used for data encryption when communicating over an IPbased network.

internetwork - The connection of two or more networks.

internetworking - Enables communications between devices attached to different networks

interoperability - The ability of systems, units, or forces to provide services, to accept services from other systems, units, or forces, and to use the services so exchanged to enable them to operate effectively together. (ATIS)

interstitial space - A small or narrow space located above or below the occupant's space on each floor that is used for routing building services (e.g., lighting; heating, ventilating, and air conditioning; power; telecommunications; plumbing).

intrabuilding backbone cable - Cable that runs between telecommunications rooms inside a building. Can be vertical or horizontal in physical orientation.

intrabuilding backbone pathway - Provides the means to connect main terminal space and telecommunications rooms within a building.

intrabuilding telecommunications backbone - A pathway or cable facility for interconnecting telecommunications service entrance rooms, equipment rooms, and telecommunications rooms within a building.

intranet - A collection of users/servers designed to provide content, via methods similar to the World Wide Web, to a limited group of users, defined by security restrictions, on an internal network.

intrusion detection - The process of detecting and tracking actual or attempted unauthorized access to a network or a protected device.

intumescent - Ability to enlarge or swell under the influence of heat.

intumescent firestop - A firestopping material that expands under the influence of heat. (TIA)

inverse multiplexing - The process of taking a large digital message and breaking it into smaller data streams for transmission on multiple smaller bandwidth media. The opposite end reverses the process and reassembles the original message.

ionosphere - A section of the atmosphere that extends from about 70 km to 500 km (43.5 mi to 311 mi) in altitude, in which ions and free electrons exist in sufficient quantities to reflect and/or refract electromagnetic waves.

isoceraunic map - A geographical map of a wide area (e.g., United States) with continuous lines connecting points of equal thunderstorm-day activity that provides a relative comparison of the thunderstorm activity in one area to that of another area.

isochronous - 1. A property of signals where the signals are dependent on some uniform timing or carry their own embedded timing as part of the signal. 2. A property of electronic systems where all devices in a network derive their timing signal directly or indirectly from the same primary reference clock.

isolation gap - A procedure that isolates the building ground from the outside plant ground by removing the armor shield from the entrance cable for a short distance and inserting a capacitor to connect from one side of the armor shield to the other side. This may be accomplished at a splice point or in the entrance cable sheath itself.

isolation transformer - A transformer with high galvanic insulation used to break ground loops at low frequency in communications systems operating over copper cables.

isolator, radio frequency - A passive device used to control the propagation of a radio frequency signal by allowing the signal to pass in one direction while providing high isolation to reflected energy in the reverse direction.

isotropic radiator - A theoretical model antenna that radiates power with identical and constant intensity in all directions from a point source. Used as a reference standard to compare the radiation properties of all other types of antennas.

issuer - The person or company that issues a request for quote or request for proposal.

jabber - An error condition caused by an Ethernet device transmitting longer frames than allowed or continuous random data.

jack - A common term for telecommunications outlet/connector. See also modular jack.

jack contact - The current-carrying metallic member in a modular jack. (TIA)

jacket - The outer layer of a cable. See also cable sheath.

jack header - A raceway similar to a header duct, usually provided in short lengths to connect a quantity of distribution ducts together. (TIA)

jackstand - A device for holding a large cable reel off the floor so the cable can be removed from the reel.

J-hook - A supporting device for horizontal cables that is shaped like a J. It is attached to some building structures. Horizontal cables are laid in the opening formed by the J to provide support for the cables.

jitter - Signal phase distortion in the time domain.

job plan - A comprehensive outline of all aspects of the project. It includes all work, material, and labor operations and scheduling, how and when the work is to be performed, how each aspect of the work will affect the remaining areas, and how the work will fit into the general contractor's construction schedule.

job site - The physical location where work is to be performed.

joint-owned pole - An outside plant pole owned by two entities.

joint random buried plant - Power, cables, and telephone cables that are placed in a common trench with little or no separation.

joint trench - A trench that contains the facilities of two or more companies.

joint use - The practice of two or more service providers (SPs) sharing the same facilities. In the case of utility poles, individual poles are typically owned by one SP, which in turn leases space to the other providers. In the United States, the CommunicationsAct of 1996 and some states' public utility commissions regulate this practice to ensure that public utility companies offer nondiscriminatory access to all other SPs.

joint-use pale - See joint use

jumper - 1. An assembly of twisted-pairs without connectors, used to join telecommunications circuits/links at the crossconnect. (TIA) 2. An optical fiber cable with connectors installed on both ends. See also cable assembly and pigtail.

jumper wire - Typically, 24 AWG [0.51 mm (0.020 in)] twisted-pair wire terminated on 66-blocks, 110-blocks, or screw terminals to join telecommunications feeder and distribution facilities at the cross-connect. See also jumper,

junction box - A location in the pathway system that allows transition of pathways and access to cables. (TIA)

key - A unique value (digital signature) associated with a specific user on a network for the purposes of network security. See also digital key.

keyed - A jack, outlet, or connector is considered keyed when it requires a specific orientation.

keying - The mechanical feature of a connector system that guarantees correct orientation of a connection, or prevents the connection to a jack, or to an optical fiber adapter of the same type intended for another purpose. (TIA)

keypad - An alphanumeric grid that allows a user to enter a personal identification code.

key service unit (KSU) - An electromechanical telephone main control unit where telephones have multiple buttons permitting the user to manually select outgoing or incoming central office telephone lines. It is not necessary to dial an access code for an outgoing line.

key system - See key service unit (KSU).

key telephone system (KTS) - Terminals and equipment in a local environment that provide immediate access from all terminals to a variety of telephone services without attendant assistance.

key telephone system (KTS) ground terminal - A screw terminal located on the key system power supply that must be connected to the grounding lug on the station protector.

k-factor - In tropospheric radio propagation, the ratio of the effective Earth radius to the actual Earth radius. The k-factor is approximately 4:3.

known user - Users with pre-established identities on a network. Contrast with unknown user.

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packet - Bits grouped serially in a defined format containing a command or data message sent over a network. A generic term used to describe a unit of data at any layer of the Open Systems Interconnection Reference Model protocol stack. See also frame and datagram.

packet assembler/disassembler (PAD) - A device that breaks a digital message into x.25 packets for transmission and reassembles a message from received packets.

packet binary convolutional coding (PBCC) - An encoding method proposed for IEEE 802.11g. Because of the peak transfer rate of 33 Mb/s, it was rejected in favor of orthogonal frequency division multiplexing. It is still included in IEEE 802.11g as an option.

packet buffer - The memory set aside for storing a packet awaiting transmission of or storing a received packet.

packet filter - A firewall that examines each network packet, or datagram, and uses an access control list to determine if the inbound or outbound datagram should be discarded (filtered) or allowed to pass through the firewall.

packet filtering - A security mechanism that examines each packet entering or exiting a network. Only the packets meeting preestablished criteria are allowed to proceed.

packet switching - A data communications switching and transmission system in which an input data stream is broken down into uniform data packets. Each packet is transmitted independently between devices through the network without first establishing a dedicated communications path between the devices. At the receiving end, the packets are checked for errors, resequenced as necessary, and combined into an output data stream. Contrast with circuit switching.

pad - A network of fixed resistors that attenuates signals by a fixed amount with negligible distortion.

padding down - Intentional attenuation of a signal.

PageFormat - A joint publication of the Construction Specifications Institute and Construction Specifications Canada that provides guidelines for the presentation of text on a page in an easy-to-read format for all sections. The use of a standardized page format provides an orderly, uniform arrangement of text for each page of any section. (CSI)

pair - 1. Two insulated wires commonly joined. They can be twisted around each other or mated together as in flat cable. 2. One side circuit (two diametrically facing conductors) in a star quad.

pair count - 1. Indicates how many pairs of grouped conductors are in a cable. 2. The pair identification of cable and pairs serving a location.

pairing - Creates keys for use on encrypted links in Bluetooth

pair scanner - See wire map tester. See also wire map

pair to pair - A configuration term used to indicate pairs going straight through (e.g., plug to plug, jack to jack, jack to plug).

pair twist - The uniform twist of an insulated copper pair that helps to reduce the negative effects of capacitance imbalance and electromagnetic induction.

panel antenna - A style of radio frequency antenna constructed in a flat panel shape. A flat panel antenna -is highly directional and usually a phased array antenna. Such antenna systems may combine signals from thousands of antenna elements to focus a beam at some angle in space.

panic bar - A push bar and latch mechanism that is installed on the secure side of an opening. When the push pad is pressed, the latch will be released and the opening will be unsecured.

paper insulation - The insulation of individual conductors in a cable with paper ribbon, either spirally or longitudinally applied. These conductors are not individually color-coded in outside plant.

parabolic antenna - A directional antenna often shaped like a dome (concave reflector) used to produce a parallel beam when the source is placed at its focus or to focus an incoming parallel beam.

parallel circuit - A circuit in which the identical voltage is presented to all components, and the current divides among the components according to the resistance or the impedance of the components.

parcel plat - A map of a single parcel of property, or a portion thereof, showing the boundaries, improvements, access, ownership, and other pertinent information.

parity - The information needed to recover the data stored on a failed disk drive in a redundant array of independent disks configuration.

parity check - An error-checking scheme that adds a bit to a block of data. When using even (odd) parity, the added bit in the block is set to either zero or one to make the total number of ones in the block, plus the parity bit, equal to an even (odd) value. Parity will detect a single error.

parked state - Refers to a slave device in Bluetooth". A parked slave is not active on the channel, but will remain synchronized to the clock of the master.

passive cross-connect - A facility enabling the termination of cable elements and their interconnection or cross-connection by means of jumpers or patchcords without modification of the transmitted signal through amplification, retiming, or regeneration. (TIA)

passive distribution equipment - Equipment that does not require electric power and does not modify the transmitted signal through amplification, retiming, or regeneration.

passive hub - A hub that does not require electrical power to operate. Such devices function as simple signal distribution units, where an incoming signal on one port is directed to another port with no amplification, retiming, or regeneration. See also active hub and hub.

patch antenna - Comprises a patch of conductive material fixed above a conductive plane and separated from the plane by a thin dielectric substrate. Patch antennas are moderately directional.

patch cord - A length of cable with connectors on both ends used to join telecommunications circuits/links at the cross-connect. (TIA)

patching - Means of connecting circuits via cords and connectors that can be easily disconnected and reconnected at another point.

patch panel - A connecting hardware system that facilitates cable termination and cabling administration using patch cords. (TIA) See also modular patch panel.

path - See pathway.

path loss - In a communications system, the attenuation undergone by an electromagnetic wave in transit between a transmitter and a receiver. It may be caused by many effects such as free-space loss, refraction, reflection, aperture-medium coupling loss, and absorption.

pathway - 1. A sequence of connections that provides the connectivity between devices on a network or between networks on an intemetwork. 2. The vertical and horizontal route of the telecommunications cable. 3. A facility for the placement of telecommunications cable. (TIA)

pavement structure - The combination of sub-base, base course, and surface course placed on a sub-grade to support the traffic load and distribute it to the roadbed.

payout box - A cardboard container with a hole for cable distribution directly from the box.

peak output power - Maximum allowable output power of a transmission source.

peak power (PP) - Maximum electrical energy available in an alternating current. It is a factor of voltage multiplied by the current (amperage). See average power and power.

pedestal - A protective aboveground enclosure used most commonly to house a splice point or administrative terminal location.

peer-to-peer local area network - A network environment where any station can contribute to or access network resources. All network devices function as equals.

penalties (contract) - Fines levied by a customer against a contractor for failure to meet terms of a contract.

penetration - Opening made in a firestop barrier. See membrane penetration and through penetration.

performance bond - A bond that ensures a contractor will use specified methods and procedures in performing a project.

performance management - The optimization of individual components and the overall network to optimize the time it takes to complete a given task.

perigee - The point at which a satellite is closest to the earth.

perimeter network - See lobby network.

perimeter-based security - Securing a network by controlling access to all entry and exit points on the network.

period - The smallest repetitive interval of a periodic wavefarm (e.g., time for one cycle of a sine wave).

peripheral - An auxiliary telecommunications device (e.g., printer, modem) that works in conjunction with a computer network.

peripheral device - External equipment connected to and controlled by a station or a server (e.g., CD-ROM drives, modems).

permafrost anchor - An anchor inserted in the ground made of a standard anchor rod with a washer on the end.

permanent link - A test configuration for a link excluding test cords and patch cords. (TIA)

permanent link test configuration - The transmission path between two mated interfaces of generic cabling, excluding equipment cords, work area cords and cross-connections but including the connecting hardware at each end. (ISO)

permanent virtual circuit (PVC) - A software-defined logical connection in a switched network in which users define logical connections and required bandwidths between end points while the switched network technology achieves the defined connections and manages the traffic. With this type of circuit, the line is always ready, which eliminates the delay associated with line setup and release. Contrast with switched virtual circuit.

personal area network (PAN) - A data communications system that covers an area generally associated with an individual workspace (e.g., office, cubicle).

personal identification number (PIN) - A unique numeric code used to identify an individual.

personal protective equipment (PPE) - Any number of safety apparatuses worn or used (e.g., hard hat, protective eyewear, gloves, clothing) that shields against possible injury while performing tasks.

personnel lift - Mechanical device for lifting construction personnel when a ladder cannot be used safely because of the required working height or weight of equipment.

PERT (program evaluation review technique) chart - A network chart or logic diagram. Generally used by the project manager to see how one change in the project affects the remaining tasks.

phantom collision - A phenomenon on twisted-pair Ethernet systems where the transmitting device detects a nonexistent collision, often caused by excessive crosstalk or electromagnetic interference.

phase alternation line (PAL) - An analog television display standard used primarily in Europe. PAL scans the cathode ray tube 625x horizontally.

phase modulation (PM) - An angle modulation in which the phase angle of a carrier is caused to depart from its reference value by an amount proportional to the instantaneous value of the modulating signal.

phase - The relationship in time between two waveforms of the same frequency.

phased array antenna - An antenna that can transmit/receive electromagnetic fields at/from any direction without any mechanical movement. Such antennas usually support broad bandwidth and carry more information. They have low visibility and are difficult to detect due to the absence of moving parts.

phased cutover - A progression of transferring an old system to a new system in a pre-defined sequence of steps. See also method of procedure.

phases (of design) - The American Institute of Architects defines design as occurring in three distinct phases: schematic design, design development, and construction documents. The Engineers Joint Contract Documents Committee defines design in two phases: preliminary design and final design phase, which includes construction documents. The Design-Build Institute of America defines design in two phases: schematic design and design development, which includes construction documents. For the purpose of this manual, design is defined as having two phases: schematic and design development. (CSI)

phase-shift keying (PSK) - In digital transmission, angle modulation in which the phase of the carrier is discretely varied in relation either to a reference phase or to the phase of the immediately preceding signal element, in accordance with data being transmitted.

physical address - See device address

physical design process - A procedure used to assess the requirements for integrating the material components of the network into the site.

Physical layer - The Open Systems Interconnection Reference Model layer responsible for the transfer of bit streams over a specific medium. Also called Layer 1.

physical medium attachment (PMA) - In Ethernet, the part of the Physical layer that controls transmission, reception, collision detection, clock detection, and skew alignment.

physical medium dependent (PMD) sublayer - The fiber distributed data interface sublayer that specifies optical power output and receiver sensitivity, cabling specifications, the media interface (i.e., connector interface), and optical bypass specifications.

physical topology - The physical layout of a network as defined by its cabling architecture. Contrast with logical topology.

piconet - A single Bluetoot wireless personal area network that can contain a maximum of eight active devices. Each master device and the slave device, or devices associated with it, form a piconet. It provides a base level of connectivity to even the simplest of sensing and computing objects. See also scatternet.

piggybacking - More than one individual entering a secure area by following an authorized user into a secure area.

pigtail - One or more conductors or fibers with only one end terminated. (TIA) See also cable assembly and jumper.

PIII-500 - A semi-rigid coaxial cable with an aluminum sheath that is typically used as a trunk cable in a CATV distribution network. This term is pronounced "P three five hundred." PII! indicates the type of cable and 500 indicates the cable diameter (13 mm [0.5 in]).

PIN diode - A positive-intrinsic-negative diode, used to convert optical signals to electrical signals in a receiver.

pinout - A wiring scheme for the individual conductors in a telecommunications connector, jack, or plug.

piston - A lightweight air-blocking agent used in conjunction with a vacuum device to insert a pullstring into a conduit.

plain old telephone service (POTS) - Basic service that supplies standard single-line telephone, telephone lines, and access to the public switched network.

plant - Used in telecommunications to refer to the cable, equipment, support structures, and other types of infrastructure necessary to provide and distribute network services (e.g., outside plant).

plaster ring - See low-voltage mounting bracket.

Plastic insulated conductor (PIC) - A metallic conductor that is insulated with a plastic material.

plastic optical fiber (POF) - Optical fiber made of plastic rather than glass. See also optical fiber.

plate anchor - An anchor composed of a rigid steel or other high-strength metal plate direct-buried in the ground.

plenum cable - See communications plenum cable.

plenum rated - Meeting flammability and smoke requirements for the purpose of fire, life, and safety as described by NFPA 70, the National Electrical Code.

plenum - A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system. (TIA)

plot plan - See site drawing. plug See modular plug.

point of demarcation - See demarcation point.

point of presence (PoP) - In wireline, the physical demarcation or access point of control and billing at an interexchange carrier, local exchange carrier, competitive local exchange carrier, customer premise equipment, or service provider.

point-to-multipoint - A wireless connection from one point to several other points.

point-to-point (PTP) - A direct connection established between two specific locations, as between two buildings or devices.

poke-thru system - A fire-rated device used to penetrate through the fire-resistive floor structure to permit the installation of electrical and/or telecommunications cables.

poke-thru - Penetrations through the fireresistive floor structure to permit the installation of horizontal telecommunications cables. (TIA)

polarity - The quality or condition inherent in a body that exhibits opposite properties or powers in opposite parts or directions or powers in contrasted parts or directions.

polarization - Orientation with respect to a given position, force, voltage, or direction. As with antennas, this is the direction of the radiated electric field in relation to the surface of the earth. This is generally vertical in mobile radio systems.

pole - A column of wood, steel, fiberglass, or other material supporting overhead cables.

pole attachment - The physical connection by which aerial cable is attached to a pole.

pole class - A rating used to classify outside plant pole strengths. See also pole.

pole dip - See cable dip.

pole number - An administration number assigned to an installed pole.

pole-to-pole guy - A steel-stranded wire that runs from one pole to another pole, as opposed to a down guy.

polybutadiene - A type of synthetic rubber often blended with other synthetic rubbers to improve their properties.

polyethylene (PE) - Thermoplastic material having excellent electrical properties and excellent environmental protection.

polymer - Substance made of many repeating chemical units or molecules.

polyolefin - Any of the polymers and copolymers of the ethylene family of hydrocarbons (e.g., polyethylene, polypropylene).

polypropylene (PP) - A thermoplastic similar to polyethylene but stiffer and having a higher softening point (temperature), primarily used as a thin wall insulation material.

polyurethane (PUR) - A broad class of polymers noted for good abrasion and solvent resistance primarily used as a cable jacket material. Good flame resistance.

polyvinyl chloride (PVC) - A tough, general purpose, flame-retardant, thermoplastic, water-resistant insulator used for wire and cable insulation and jackets.

port - 1. A physical connection point on a network access device (e.g., hub, switch). 2. An identifier of an application process within the Transmission Control Protocol/Internet Protocol suite.

portable operator's terminal (POT) - A portable terminal used for maintenance and error detection in building automation systems.

port aggregation - A mechanism that combines multiple network communications channels into a single large channel to improve data transfer efficiency. See also link aggregation and trunking.

portal - An access point that connects a wireless LAN to another IEEE 802 network (e.g., Ethernet, token ring).

port density - The number of modular connections within a space.

port mirroring - The process of copying the data passing through one or more ports of a switch to a network management port for monitoring purposes.

port trunking - See link aggregation.

position bonding terminal - A device located in the work area that electrically bonds cabling or cabling and equipment to ground. (TIA)

positive-intrinsic-negative (PIN) diode - See PIN diode.

positive temperature coefficient (PTC) resistor - A resistor whose resistance increases with temperature.

poststressed concrete - Concrete poured into a mold with metal cables exposed at each end.

posttensioned concrete - A type of reinforced concrete construction in which the embedded steel members are first put under tension, the concrete poured and allowed to harden, and the tension of the steel members released causing compression of the concrete. (TIA)

pothole - See test hole.

powder-actuated fastener - A device used to attach material to concrete or steel that is installed using a powder actuated drive tool.

power (P) - 1. Rate of transfer or absorption of energy per unit time in a system. 2. Energy required to operate an electrical device (e.g., motor, amplifier, telephone transmitter). See also average power and peak power.

power arrester - A device installed in power systems to limit the line-to-ground surge due to a power surge or spike.

power attachment - A pole attachment specifically made with aerial power hardware.

power budget - The difference between the strength of the signal transmitter and the sensitivity of the signal receiver.

power over Ethernet (PoE) - A feature associated with twisted-pair Ethernet networks that allows the network access device to be powered over the network wiring. Injectors are used to insert power into the line at a central point.

power splitter - A passive device that accepts an input signal and delivers multiple output signals with specific phase and amplitude characteristics.

power sum alien equal level far-end crosstalk (PSAELFEXT) - A computation of the unwanted signal coupling between pairs in adjacent cabling from multiple transmitters at the near end into another pair measured at the far end and relative to the received signal level.

power sum alien far-end crosstalk (PSAFEXT) - A computation of the unwanted signal coupling between pairs in adjacent cabling from multiple transmitters at the near end into another pair measured at the far end and relative to the received signal level.

power sum alien near-end crosstalk loss (PSANEXT) - A computation of the unwanted signal coupling between pairs in adjacent cabling from multiple transmitters at the near end into a pair measured at the near end.

power sum attenuation-to-crosstalk ratio (PSACR) - A ratio in dB, determined by subtracting the insertion loss from the power sum near-end crosstalk loss. (TIA)

power sum equal level far-end crosstalk (PSELFEXT) - A computation of the unwanted signal coupling from multiple transmitters at the near-end into a pair measured at the far-end, and normalized to the received signal level. (TIA)

power sum near-end crosstalk (PSNEXT) loss - A computation of the unwanted signal coupling from multiple transmitters at the near-end into a pair measured at the near-end. (TIA)

power sum - Used to specify a combination crosstalk from multiple sources.

power-limited (PL) - Refers to secondary power (subcircuit) reduced to 24 volts direct current or less for building automation system functions.

power-limited fire alarm (PLFA) - Fire alarm systems that utilize low-voltage circuits (less than 24 volts).

power-line carrier (PLC) - A technology that sends electronic information (e.g., on/ off commands) through a home's alternating current power lines.

precable - See prewiring.

precast concrete - A concrete member that is cast and cured in other than its final position.

prefusing - The machine cleaning of the optical fiber ends prior to performing a fusion splice.

preinstallation meeting - Internal meeting convened by the project manager and including the telecommunications installation team and appropriate contractors to discuss all aspects of upcoming construction project.

premises - Building or set of buildings on common property that are occupied by a single tenant or landlord.

premises cabling - A generic term that includes interbuilding backbone cabling, intrabuilding backbone cabling, and horizontal cabling that is owned by a single tenant or landlord. Refers to the entire cabling system used for voice, data, video, and power on a user's premises.

premises wiring - See premises cabling.

Presentation layer - The Open Systems Interconnection Reference Model layer responsible for various forms of message conversion, including compression and encryption. Also called Layer 6.

preset insert - See insert, preset.

pressure transducer unit - A stepped switch instrument that converts cable pressure to electrical resistance.

pressurization - The use of pressurized gas or dry air inside cable sheaths to prevent the entry of moisture.

prestressed concrete - Concrete poured into a mold containing tension rods or cable.

prevailing wage rate - Labor rates published by state or federal governments that state the minimum allowable wage that can be paid to a laborer for a particular task, typically on a publicly funded project. The rates are published for each project and can vary from county to county and project to project.

prewiring - 1. Cabling installed before walls are enclosed or finished. 2. Cabling installed in anticipation of future use or need. See also rough-in.

primary power system - The power distributed from an electric generation station usually consisting of three phased, 2,200 volts, 7,200, 13,800 volts, or higher.

primary protector - 1. A device that limits voltage between telecommunications conductors and ground (usually between 215 Vdc to 350 Vdc). 2. A protective device placed on telecommunications conductors in accordance with codes and standards such as NFPA 70.

primary rate interface (PRI) - An integrated services digital network (P/ISDN) interface standard that, in the United States, consists of 23 64 kb/s B channels and one 64 kbls D channel using a T-1 line. In Europe, P11SDN consists of 30 64 kb/s B channels and one 64 kb/s D channel using an E-1 channel.

prime contractor - The master contractor on a job site that may be serviced by several general contractors.

principal - The party who has the primary obligation to perform the undertaking that is being bonded. For example, the contractor on a bonded construction project is the principal. (CSI)

prioritization - A function performed by a network interface card that makes it possible to assign different levels of priority to the applications running simultaneously on a station. Also called traffic prioritization.

privacy mode - In demand priority access communications, a mode in which an end node receives only those messages containing its address. See also promiscuous mode.

private automatic branch exchange (PABX) - A private telecommunications switching system. (TIA)

private branch exchange (PBX) - A private telecommunications switching system allowing private local voice (and other voice-related services) switching over a network. (TIA)

private key encryption - A security process in which information is encrypted with a key that both the sender of the information and the receiver possess. The parties involved are expected to agree on a key in a way that does not compromise the established security processes. See also public key encryption.

probe - See agent.

program evaluation review technique (PERT) chart - See PERT chart.

programmable card - A card on which data may be encoded.

program material - The video and audio material that is broadcast over a cable system.

project log - A written log of everything that happens on a project hour-by-hour, dayby-day, or item-by-item.

project plan - Construction plan reflecting all aspects of the work to be performed using a priority schedule.

project record documents - Project record documents include contract drawings, the project manual, addenda, contract modifications, submittals, product data, shop drawings, samples, start-up logs, test reports, certifications, and other documents from the contractor. (CSI)

project schedule - 1. A chronological order of events that will be accomplished on a project and in the order that they must occur (should be descriptive in text, not a definition). 2. Scheduling document including all activities to take place in a construction project.

promiscuous mode - A network access mode in which an end node receives all message traffic transmitted over the network. See also privacy mode. (TIA)

propagation - The motion of waves through or along a medium.

propagation delay - The time required for a signal to travel from one end of the transmission path to the other end. (TIA)

propagation velocity -The speed at which a signal travels in a medium.

proposal - A detailed offer of services and/ or resources, usually in exchange for other services or monies.

proprietary specifying - Specifies actual brand names, model numbers, and other proprietary information. A proprietary specification describes products and materials by manufacturer's name, brand name, model number, or unique characteristic. Closed proprietary specifications do not allow for substitutions, but open proprietary specifications allow for alternative products. (CSI)

protected premises - 1. The physical location protected by a fire alarm system. A protected premises system sounds an alarm at the protected premises as the result of the manual operation of a fire alarm box or the operation of protection equipment or systems, such as water flowing in a sprinkler system or the detection of smoke. 2. Provides a hierarchy of rights and/or privileges for different user groups and their associated authorized zones.

protected system - A wireless system that provides redundancy by using a transmitter combiner to connect two transceivers to an antenna for redundancy. See also protected and diversity and unprotected system.

protective switching - A function performed by asynchronous transfer mode switches to redirect traffic away from routes experiencing difficulties.

protector - A device that prevents damage to lines or equipment by conducting hazardous high voltages or currents to ground. Most protectors come in assemblies containing fusible link stubs and the housing and circuitry for individual protector units.

protector (cable) - An outside plant protector that limits the voltage between the conductors and shield of a cable.

protector (ground conductor) - A wire run from the ground lug on the protector to an approved ground via the shortest and straightest route.

protector (open wire) - An outside plant protector that limits the voltage between open wire telecommunications conductors and ground.

protector bond - A bond of a grounding conductor to a protector.

protector unit - A replaceable voltageshunting device that is inserted on each cable pair in a protector assembly. The units come in a variety of types based on clamping voltages and reaction time.

protocol - A set of rules and procedures governing the formatting of messages and the timing of their exchange between devices on a network covering addressing, transmitting, receiving, and verifying.

protocol data unit (PDU) - Describes the format of data exchange between layers in a protocol stack.

protocol implementation conformance statement (PICS) - A document listing the exact features and options from a standard that has been implemented in a particular network element.

protocol stack - A comprehensive set of specifications that define how network hardware and software interact at various levels to transfer messages between devices on a network (e.g., OSI Reference Model).

provisioning - The setting in place and configuring of the hardware and software required to activate a telecommunications service for a customer.

proximity - A method of reading a card without requiring any physical contact between the card and the reading device.

proximity card - A card using proximity technology to store and transmit encoded data.

proxy - A security mechanism that uses an intermediary device to represent one side of a connection to the other for a specific application. Messages and commands intended for the other side are inspected by this device before being forwarded to prevent unauthorized use of that application.

proxy server - A firewall security mechanism that functions as an intermediary device to represent one side of a connection to the other for a specific application. Messages and commands intended for the other side are inspected by this device before being forwarded to prevent unauthorized use of that application.

psophometric noise - The audible noise measured in telephone lines within the audible frequency range (usually between 300 Hz and 3,400 Hz) evaluated based upon standardized weight factors for each key frequency within the frequency range of interest. The psophometric noise voltage is usually measured across a noninductive resistor of 600 ohms terminating the line at the place of measurement.

psophometric weighting - A noise weighting established by the International Consultative Committee for Telephony (CCIF, which became CCITT and, more recently, ITU-T), designated as CCIF-1951 weighting, for use in a noise measuring set or psophometer.

psophometrically weighted - See noise weighting and psophometric noise.

public key encryption - A security technique in which a user is assigned two related keys. One key is held privately and the other key is distributed publicly. Anyone wishing to send a confidential message to the user encrypts it with the user's public key. When the message is received, the user decrypts it with the corresponding private key. See also private key encryption.

public opening - An opening of request for quote responses (bids) at which all respondents may be present.

public switched telephone network (PSTN) - A domestic telecommunications network usually accessed by telephones, key telephone systems, private branch exchange trunks, and data arrangements.

pull - 1. The act of placing cable by pulling. 2. The longitudinal force acting on a pole as a result of horizontal loading.

pull box (PB) - A device to access a closed raceway used to facilitate placing of wire or cables.

pull cord - A cord, string, wire, or tape placed within a cable pathway and used to pull wire and cable through the pathway.

pulled - Call in or cash in of a bond because of a stated reason.

pulling eye - A factory-installed device on a length of cable to which a swivel eye and pull rope are attached.

pulling iron - An attachment installed in maintenance holes to provide a point of connection for blocks, sheaves, and other devices used for pulling cable into the duct system.

pulling sheave - A pulley having a grooved rim for retaining a rope or cable,

pulling technique - Collectively refers to the methods and materials employed to install cables.

pull point - Location where it is possible to physically access the cables to pull them.

pull rope - A rope or mule tape used to obtain an increased amount of strength for pulling heavier amounts or high pair-count cables.

pull strength - The rated strength of the force of a cable that can be exerted on it during the pulling process. See also pull tension.

pull string - A cord or wire placed within a cable pathway and used to pull wire and cable through the pathway. See also drag line and pull cord.

pull tension - The pulling force that can be applied to a cable. (TIA)

pull wire - See drag line and pull cord and pull wire.

pulp insulation - The separation of individual conductors in a cable with insulation material composed of wood pulp.

pulse - A rapid, transient change in amplitude of a digital signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value.

pulse amplitude modulation 5 level (PAM-5) - A form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. Demodulation is performed by detecting the amplitude level of the carrier at every symbol period. PAM-5 is used for 1000BASE-T transmission.

pulse amplitude modulation 12 level (PAM-12) - A form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. Demodulation is performed by detecting the amplitude level of the carrier at every symbol period. PAM-12 is used for 10GBASE-T transmission.

pulse code modulation (PCM) - A technique for representing an analog signal as a string of bits. The analog signal is converted to a bit string by periodically sampling the amplitude of the analog signal and representing each sample as a binary number.

pulse repetition rate (PRR) - The number of pulses per unit time.

punch down - The process of terminating copper cable conductors on insulation displacement contact terminals by use of a handheld tool,

punch list - A short list of tasks that are required to be completed in order to close out a work order.

punch lists - Punch lists are lists of items requiring correction or completion by the contractor. The initial punch list is prepared by the contractor prior to requesting substantial completion. During the architect or engineer's (A/E) inspection to determine substantial completion, the A/E prepares a supplemental punch list. These two punch lists combined are the final punch list. (CSI)

push brace - Where guying is not feasible, bracing is provided by use of a pole of an equivalent type to the pole being reinforced.

pWp - Picowatts of noise power, psophometrically weighted. 1.0 pWp is equivalent to an 800 Hz test tone at -90 dBm.

quad cable - A cable with four insulated, copper, nontwisted strands. Typically, the conductors are color coded red, green, black, and yellow. Also called quad.

quadrature amplitude modulation (QAM) - A means of encoding digital data that uses variations in signal amplitude and phase. QAM signals have 2z" states, where each state encodes 2N bits. The encodings most commonly used include QAM-4, QAM-16, QAM-64, and QAM-256.

quadrature phase shift keying (QPSK) - Phase-shift keying in which four different phase angles are used. In QPSK, the four angles differ in phase by 90 degrees.

quad-shielded - A cable consisting of a foil-braid-foil-braid shield.

quality of service (QoS) - 1. A commitment to performance, based on predefined service parameters. 2. A measure of the level of service provided on a network.

quarter common intermediate format (QCIF) - A videoconferencing format that specifies data rates of 30 frames per second, with each frame containing 144 lines and 176 pixels per line. This format is defined in ITU-T Recommendation H.261.

quarter common intermediate format/ quarter standard input format (QCIFI QSIF) - A videoconferencing format that specifies data rates of 30 frames per second, with each frame containing 144 lines and 176 pixels per line. QCIF support is required by the ITU H.261 videoconferencing standard. See also common intermediate format/standard input format.

quarter-wave antenna - A radio antenna that is one-fourth the size of the wavelength of the design frequency.

quartet - A grouping of 4 bits. See also nibble.

queuing - A quality of service technique that classifies data by priority and stores it in a queue prior to processing.

quote - See proposal.

raceway - Any enclosed channel designed for holding wires or cables.

rack - See cable rack.

rack unit (RU) - A unit of measure of vertical space in an equipment rack. One rack unit is equal to 45 mm (1.75 in).

radiating cable/leaky coaxial cable (LCX) - A coaxial cable with an outer conductor into which slots are cut that allow ingress and egress of signals within a limited range of the cable.

radiation pattern envelope (RPE) - A graphical representation of radiation properties of an antenna as a function of space coordinates.

radio frequency (RF) - The group of electromagnetic energy within the electromagnetic spectrum whose wavelengths are between the audio and the light range (usually between 535 kHz and 300 GHz).

radio frequency (RF) dispersion - A term used to describe any process by which radio frequency signal propagating in the air is degraded because the various wave components (i.e., frequencies) of the signal have different propagation velocities.

radio frequency identification (RFID) - A generic term for technologies that use radio waves to automatically identify people or objects.

radio frequency interference (RFI) - The disruption of radio signal reception caused by any source which generates radio waves at the same frequency and along the same path as the desired wave.

radome cover - An antenna cover that safeguards the antenna against environmental concerns and has low loss characteristics.

radome loss - The sum of the ordinary insertion loss of the antenna signal passing through the radome wall plus the scattering loss off the radome panel framework blocking (shadowing) the antenna aperture.

rake receiver - Used in a code division multiple access multipath environment to counter multipath effects. Identifies and combines received multipath signal components using estimated delays and weighting factors.

random spacing - Occurs where telephone cable is buried in the same trench with power conductors and no deliberate attempt is made to maintain a separation between the two systems.

rat - See piston.

Rayleigh scattering - The deflection of light from the path it would follow if the refractive index were uniform or gradually graded. Caused primarily by micro defects, impurities, and molecular structure in the optical fiber.

reader - A device that receives an identification code from a card.

real-time - The recording, processing, storage, transmission, and viewing of a message created by an activity as it occurs. Contrast with store-and-forward.

rearrangement - An action taken to replace, add, adapt, or remove existing premises wiring system components.

rebar - See reinforcing bar.

receiver - An electronic device that detects and demodulates and amplifies transmitted signals.

receiver, optical - An optoelectronic circuit that converts an optical signal to an electrical serial logic signal.

receiver sensitivity - A specification of the minimum input signal power that is required to achieve an output signal power that meets a specified performance criterion (e.g., bit error rate).

reciprocity - A principle by which an antenna behaves in the same manner whether receiving or transmitting.

record - The permanent documentation of installed telecommunications infrastructure obtained from as-builts.

recycle time - The time needed to reset and reinstate the timing function and remain within the specified timing tolerances. Recycle time is generally specified "during timing" or "after timing."

red iron - A structural steel assembly painted with five coats of zinc oxide paint, or prerusted for a specified time in the open environment.

redirector - See shell.

reel dolly - See jackstand.

redundant array of independent disks (RAID) - A technology that makes it possible to group together multiple hard disk drives and allow them to function as a single storage unit. Different configurations (levels) of RAID provide varying amounts of data redundancy arid performance.

reel brake - A device used to control the rate of removal of a cable from a cable reel.

re-fish (conduit) - To repeat the process of installing one or more pull strings or cables into a conduit.

reflection - The abrupt change in direction of light as it travels from one material into a dissimilar material. See also Fresnel reflection.

reflection coefficient - Ratio of the amplitude of the reflected wave and the amplitude of the incident wave.

reflective break - Reflection at an optical fiber cable break caused by the abrupt change in the index of refraction. See also Fresnel reflection.

reflector - In a radio frequency antenna, one or more conducting elements or surfaces that reflect incident radiant energy.

refraction - The angular change in direction of a beam of light at an interface between two dissimilar media or a medium whose refractive index is a continuous function of position (graded-index medium).

refractive index - See index of refraction.

Registered Communications Distribution Designer (RCDDI) - A designation for individuals who demonstrate expertise in the design, integration, and implementation of telecommunications (voice, data, video, audio, and other low-voltage control) transport systems and their related infrastructure components.

registered jack (RJ) - The FCC Part 68 registration program for jacks. Specifies the type of jack, the number of pins to be used, and how the pins are wired.

reinforced concrete - A type of construction in which steel (reinforcement) and concrete are combined, with the steel resisting tension and the concrete resisting compression.

reinforcing bar - A steel bar or rod used in concrete construction to provide additional strength. Also called rebar.

relay rack - A vertical metallic frame or equipment bay that is equipped with threaded holes at a predefined spacing, in accordance with EIA-310-D.It can be floor mounted (free standing) or wall mounted.

reliability - The predictable behavior of a network during operation.

remodulator - A device that receives transmissions and converts them to the baseband level.

remote access - A form of resource access that connects a stand-alone personal computer to a LAN over an extended distance.

remote access interface card - An interface card used to connect a remote access server to one or more telecommunications circuits. Also called a wide area interface card.

remote alarm - A visual or audible signaling device used to signal violations at locations removed from the central control station or monitored openings. For example, a remote alarm may be placed on a roof, in a stair tower, or in a guard station outside of a building.

remote authentication dial-in user service (RADIUS) - An authentication and accounting system used by many Internet service providers (ISPs). A usemame and password must be entered when dialing in to the ISP. This information is passed to a RADIUS server, which checks that the information is correct and then authorizes access to the ISP system.

remote authentication dial-in user service (RADIUS) server - A server for remote user authentication and accounting. Its primary use is for Internet service providers, although it may be used on any network that needs a centralized authentication and/or accounting service for its workstations.

remote client software - Software that makes it possible for a remote station to function in the same manner as a local station. See dialer.

remote control - A form of remote access where the remote station connects to a local station and controls its operation. Contrast with remote node.

remote node - A network connection that utilizes remote access.

remote procedure call (RPC) - A protocol allowing one computer on a network to request services from another computer on the network.

remote station - A station that connects to the network over a telecommunications circuit. See also local station and station.

repeater - A device that regenerates a digital signal. A repeater receives a signal from one source, reads it, generates a completely new signal identical to the original, and transmits it to the next destination. Repeaters can be separate devices to boost long-haul transmissions or can be incorporated into other devices such as switches and routers.

request for information (RFI) - A written request for clarification or information about the contract documents, products, or services offered. It may be issued from a supplier of products or services or it may be issued by the customer.

request for interpretation (RFI) - See request for information.

request for proposal (RFP) - A detailed document of requested services and equipment of a buyer submitted to others for responses.

request for quotation (RFQ) - A detailed document that solicits quotes for projects or equipment and provides vendors with all the information necessary to prepare a quote.

request to exit (RX) signal - A signal that informs the controller that someone has requested an exit from the secure area.

request to exit (RX) switch - Utilized with an access control system, this switch is located on the secured side of a controlled door.

request to send (RTS) - A frame type used to request permission to transmit. The response is a clear-to-send signal if the wireless medium is available for transmission.

resident - The individual responsible and accountable for the telecommunications services provided to the premises who may reside on the premises or, in the case of a rental unit, be the owner or property manager.

residential gateway - A device that enables communication among networks in the residence and between residential networks and service providers' networks.

resilient packet ring (RPR) - A technology implemented using a dual-ring topology with data transfer taking place at all times using both rings. In the event of a fault on one ring, all traffic is transferred to the second ring.

resilient route - See alternate route and diverse route.

resistance - A measure of opposition a material offers to the flow of direct current.

resistance unbalance - The difference in resistance, expressed in ohms, between the conductors of a pair. May also be expressed in terms of percentage by the ratio of unbalance in ohms to the lowest conductor resistance.

resistivity - Resistance per unit of measure. Measure can be of length (e.g., 100 ohms).

resource access - The process of providing a remote user the means to connect to a LAN and obtain the same privileges as when connecting from local stations. See also content access and transactional access.

respondent - A person or company that submits a proposal in response to a request for quote.

response due date - The date by which a response to a request for quote must be received in order to be valid.

retainage - A percentage of a total contract that is withheld from a contractor until the entire scope of work is completed.

retrofit - 1. To furnish a device or system with new parts or equipment not available at the time of manufacture. 2. The installation of a structured cabling system into a preexisting residential structure.

retrofit ring - See low-voltage mounting bracket.

retrofitting - To modify systems that are already in service using parts made available after the time of original installation.

return loss - A ratio, expressed in dB, of the power of the outgoing signal to the power of the reflected signal. When the termination (load) impedance does not match (equal) the value of the characteristic impedance of the transmission line, some of the signal energy is reflected back toward the source and is not delivered to the load; this signal loss contributes to the insertion loss of the transmission path, and is called return loss.

return-to-zero (RZ) - A pulse code modulation line-encoding scheme that uses zero volt as a valid logic (binary) state.

reverberant sound - Sound that is reflected from a surface (e.g., wall, floor) to the listener.

Reverse Address Resolution Protocol (RARP) - A Transmission Control Protocol/ Internet Protocol (IP) providing the IP address when the media access control address is submitted.

reverse firewall - A firewall implemented in a reverse configuration where policies that apply to traffic exiting the organizational network (e.g., Internet access rules for employees) are enforced.

reverse proxy - See Web site acceleration.

reversed pair - A condition in which the conductors in a pair are terminated in the wrong sequence (i.e., tip connects to ring and ring connects to tip).

ribbon cable - 1. An assembly of conduc tors laid side by side in a geometric plane and fastened together. 2. Cable in which many optical fibers are embedded in a plastic material in parallel, forming a flat ribbon-like structure.

rigging - A system of ropes or pulleys used to move material and equipment.

right-of-way (RIW) - A route across public or private lands over (or under) which telecommunications facilities can be legally installed and maintained.

ring - A means for identification of one conductor of a pair. Historically associated with the wire connected to the ring portion of an operator's telephone plug. See also tip.

ring in (RI) - A port on a token ring concentrator that receives signals from the main ring path on the network cable and transmits them to the downstream ring out port or network device. It also provides connectivity to the backup path on the network.

ring laser gyroscope (RLG) - A gyro with no moving parts that uses the interference of laser light within a bulk optic ring to detect and measure changes in orientation and spin.

ring latency - In token ring, the number of bit times it takes for a signal to propagate one time around the ring. This value is the sum of the signal propagation delay through the medium plus the sum of the delays associated with every device attached to the ring.

ring network - See ring topology.

ring out (RO) - A port on a token ring concentrator that transmits signals to the main ring path on the network cable and receives them from the upstream ring in port or network device. It also provides connectivity to the backup path on the network.

ring segment - A section of a token ring communications path that is bounded by repeaters or converters. These boundaries are used to determine the signaling limits that apply to the devices within the segment.

ring topology - A physical or logical network topology in which nodes are connected in a point-to-point serial fashion in an unbroken circular configuration. Each node receives and retransmits the signal to the next node.

ringing tool - A device used to remove cable sheaths.

riser - 1. Vertical sections of cable (e.g., changing from underground or directburied plant to aerial plant). 2. The space used for cable access between floors.

riser cable - See backbone cabling.

riser closet - See telecommunications room.

roadbed - The graded portion of a roadway upon which the base course, surface course, shoulders, and median are constructed.

roaming - 1. In cellular technology (mobile telephony technology), the use of a wireless telephone outside a specified tariffed geographic area defined by the service provider (which is usually called the "home" area); outside of the home area, additional charges usually apply. 2. In wireless LAN technology, this refers to the ability to move seamlessly between the wireless cells from adjacent access points while remaining connected to the network.

rodding - Pushing or pulling a mandrel or duct brush through a conduit, using poles or rods thatjoin together to determine if the pathway is clear and can be used to install a pull string.

roll bar - See mandrel.

rolling cut - A cutover where the crossconnects are relocated one pair after another.

root repeater - In demand priority access method, the Level 1 or topmost repeater in a cascade of repeaters.

rough-in - 1. Cabling installed before walls are enclosed or finished. 2. Cabling installed in anticipation of future use or need. 3. The time in which a residential cabling installer runs the cable between the various termination points, the main task during this period being to complete all the work that is difficult to do once interior ceiling and wall materials are installed.

route loop diversity - A type of loop diversity that assigns circuits along entirely different cable paths to a building.

router - An intemetworking device, operating at the Network layer of the Open Systems Interconnection model, used to direct packets from one network to another.

router table - A database made up of information on the routes a packet can take through an internetwork.

rule of percentage - If a retrofit, the authority having jurisdiction may determine the percentage of existing cable permitted to be removed from the building without requiring a complete replacement of existing cable.

runt - A short, invalid Ethernet frame typically caused by a collision.

saddle - A device for establishing the position of the raceway or raceways within the concrete relative to the screed line and for maintaining the spacing between the raceways.

safety grounding wand - Electrical protective device consisting of an insulated handle with a metal tip that is connected to an insulated cable with a large metal clip on the opposite end; the clip is connected first to a ground source and the metal tip is used to short any transient voltages left on a de-energized circuit.

safety margin - A power loss (dB) value used to assure optical fiber cable performance criteria will be satisfied over the life of the network. Includes expected losses in source power, splice losses, and wear and tear of connectors. See also loss budget.

safety plan - A plan prepared by a company and put in place before beginning any work operation, covering all safety issues likely to arise on a particular job site.

sag - 1. A decrease in nominal root mean square voltage or current lasting 0.5 cycles up to one minute. 2. The difference in height between an aerial cable mounting and the height of the cable above the surface at its lowest point (mid-span).

sally port - See interlock.

satellite closet - See telecommunications room.

satellite room - See telecommunications room.

S-band - The frequency spectrum from 1.55 to 3.9 GHz.

SC connector - See subscriber connector.

scalability - The ability of a network to grow without degradation of quality.

scanner - A device that verifies cabling segments for wiring scheme compliance (e.g., opens, shorts, crossed, reversed, split pairs). The device may also measure cabling segment length and performance.

scattering - The deflection of light by small particles or inhomogeneities whose size is similar to or smaller than the wavelength of light. See also Rayleigh scattering and Mie scattering.

scatternet - Consists of two or more piconets in a common area, where each piconet contains at least one Bluetooth® device that is part of two or more piconets.

schematic design - A design phase that follows preliminary planning and scope development and occurs prior to design development. (This phase typically takes the design to about 30 percent).

schematic diagram - A structural or procedural diagram used in association with telecommunications and electrical systems.

scintillation - In free space optics, describes the temporal and special variations in light intensities caused by differences of refractive index along the propagation path due to slight temperature variations among different air pockets.

scissor lift - Personnel lift composed of a working platform mounted on a large scissor jack.

scope of work (SoW) - A document that provides detailed statements and descriptions of the work content for the project requirements.

screed line - The line to which poured concrete is leveled.

screen - A thin metallic wrapping (e.g., aluminum foil) used to isolate cable pairs from interference. See also foil shield.

screened subnet - See lobby network.

screened twisted-pair (ScTP) cable - Cable made up of one or more pairs of twisted copper conductors with an overall foil shield and drain wire. The entire assembly is covered with an insulating sheath (cable jacket). Also called foil twisted-pair cable.

screened/foil twisted-pair (SIFTP) cable - A cable with one or more pairs having an overall braid screened cable with individual foil screened balanced twisted-pairs. This cable construction is common in category 7/class F cabling.

scribing tool - Used to scratch the surface of a fiber to facilitate a clean break in preparation for polishing.

scripting - The process of determining which configuration tasks can be performed unattended and then automating the process.

second generation (2G) mobile telephony - A worldwide implemented digital wireless voice technology that provides 9.6 to 14.4 kbls circuit-switched data service. 213 wireless systems may offer auxiliary services (e.g., fax, short message service). Most 213 protocols offer different levels of encryption

secondary power - Power operating at less than primary power voltage.

secondary power system - The power derived from the primary power lines through the use of distribution or stepdown transformers to reduce the primary line voltage to a lower secondary voltage suitable for commercial and residential service.

secondary protector - A secondary current and voltage protector installed in series with the indoor telecommunications cabling between the primary protector and the equipment. The secondary protector may provide over current and over voltage protection.

secondary test - After acceptance testing, additional tests that are conducted to diagnose a problem or verify the cabling to additional requirements.

secret key encryption - See private key encryption.

section throw - Splicing of a new section of cable at both ends into existing cable plant.

sectional drawing - Drawing as if a vertical cut was made through the materials indicating relationships, connections, and transitions.

SectionFormat - A guide published by the Construction Specifications Institute that describes the recommended uniform approach to organizing specifications text contained in a project manual by establishing a structure consisting of three primary parts: administrative (general), physical (products), and productive (execution).

sector antenna - An antenna used to provide coverage over only a sector of the azimuth range. Used on cellular towers.

secure server - A server that requires the use of a security protocol (e.g., securehypertext transfer protocol) during a communications session.

secured side - The area or side of an opening that is locked and requires a key card or other means to enter.

security (network) - Protection against unauthorized activities, generally requiring a combination of access controls, data integrity, and transaction confidentiality.

security and access control (SAC) - Equipment associated with systems used to monitor and control devices (e.g., card readers, door alarms, closed circuit television).

security management - The protection of network resources, including physical devices, operating systems, applications software, organizational data, and network operations.

security policy - The set of principles, rules, and practices that are used to implement security in an organization.

segment - 1. A portion of a network sharing a continuous length of cable. 2. A data unit created at the Transport layer of the Open Systems Interconnection Reference Model. It contains the data and control information necessary to transfer a message from one device to another on the same network. 3. An electrically continuous network created within a hub or other similar device. 4. A single broadcast domain or token-passing section. See also datagram and frame.

segmentation - The process of dividing a LAN into multiple independent segments to improve overall data transfer rates.

self-test - A feature of equipment to run programs at their start-up or at regular intervals to test its own operation.

sensitivity - 1. In optical fiber receivers, the minimum power required to achieve a specified bit error rate. See bit error rate. 2. In an electronic device (e.g., communications system receiver, detection device, PIN diode), the minimum input signal required to produce a specified output signal having a specified signal-to-noise ratio, or other specified criteria.

Sequential Couleur avec Memoire (SECAM) - An analog television display standard used primarily in France and former Soviet Union countries. SECAM scans the cathode ray tube 525x horizontally.

serial port profile (SPP) - The protocols and procedures that shall be used by devices using Bluetooth° for RS232 (or similar) serial cable emulation.

series circuit - A circuit where the devices are arranged in a chain, with only one path for the signal or current to follow.

Series 6 coaxial cable - Having a center conductor measuring approximately 18 AWG [1.0 mm (0.039 in)], it supports similar applications as Series 11 coaxial cable; however, over a shorter distance due to increased insertion loss (attenuation) characteristics. Typically used for drop cabling. Formerly called RG-6.

Series 11 coaxial cable - Having a center conductor measuring approximately 14 AWG [1.6 mm (0.063 in)], it supports similar applications as Series 6 coaxial cable; however, over a greater distance due to reduced insertion loss (attenuation) characteristics. Typically used for backbone cabling. Formerly called RG-11.

server - A network device that combines hardware and software to provide and manage shared services and resources on the network.

service clearance - The space encompassing the equipment, or unit, that is required to permit proper working room for operating, inspecting, and servicing equipment.

service discovery profile (SDP) - Discovers from other Bluetooth6 devices such as printers or fax machines, Bluetooth services such as cordless telephony, file transfer profile, or headset profile.

service entrance - See entrance facility (telecommunications).

service equipment (power) - The necessary equipment, usually consisting of a circuit breaker or switch and fuses, and their accessories, located near the point of entrance of supply conductors to a building or other structure, or an otherwise defined area, and intended to constitute the main control and means of cutoff of the electrical supply.

service fitting - An outlet box to house the connections for telecommunications at the user work area. See also insert.

service loop - A surplus of cable, typically located at or near the point of termination to facilitate potential future changes.

service provider (SP) - The operator of any service (e.g., application programming interfaces) that furnishes telecommunications content (transmissions) delivered over access provider facilities. See also access provider (AP).

service set identifier (SSID) - A character string used for identification of a service set. Service sets must have identical SSIDs to establish radio contact. See basic service set and independent basic service set.

service wire - An underground or aerial cable that connects a serving outdoor terminal to a building or structure.

servo - A transducer that converts coded electrical signals into precise angular or linear motion.

Session layer - The Open Systems Interconnection Reference Model layer responsible for providing services used to organize, synchronize, and manage a given message exchange between network devices. Also called Layer 5.

setscrew coupling - Couplings that are placed over the ends of conduit with little or no friction. Once the end of the conduit is seated into the coupling, two screws are tightened on the outside of the coupling, causing the coupling to become firmly attached to the conduit.

shadowing - See disk mirroring and mirroring.

shallow room - An enclosed space for housing cable terminations, crossconnect cabling, and telecommunications equipment.

shared tenant service (STS) - Consolidates individual-line subscribers using a common premises switch.

shear lock magnetic lock - A modification of the direct hold magnetic lock that utilizes both magnetic and physical properties for locking. The electric magnet's lock body is mortised into the door's frame and the armature is mortised into the door edge. Indentations in the armature receive protrusions in the lock body.

sheath - See cable sheath.

sheath (cable) loop diversity - A type of loop diversity that assigns circuits among different sheaths or cables.

shell - A software-controlled interface between a user and an operating system. The shell software examines commands and user interaction for access to remote resources, processing the requests via the operating system.

shield - A metallic layer (e.g., copper braids, metal foils, solid tubing) placed around a conductor or group of conductors.

shield coverage - The percentage of a conductor's surface area actually covered by shielding material.

shielded enclosure cabinet - A metal electronics cabinet constructed with welded seams and conductive gaskets on the doors that serve as an effective shield against electromagnetic radiation.

shielded twisted-pair (STP) cable - Cable made up of multiple twisted copper pairs with an additional metallic shield covering each individual pair. The entire structure is covered with an overall shield or braid and an insulating sheath (cable jacket).

shield effectiveness - See shielding effectiveness.

shielding effectiveness - Expressed in terms of a cable's transfer impedance shielding effectiveness, it is the ratio of the voltage applied to the shield to the current flowing through the shield.

shop drawing - These drawings may be prepared by the contractor, subcontractor, or material/equipment supplier, and show how a particular aspect of the work is to be fabricated or installed.

short - A low-resistance connection between two conducting materials.

short circuit - An accidentally established low-resistance connection between two points in an electric circuit.

shorting bar - Used to loop a signal between two discrete contacts.

shorting plug - A device to create a direct connect between two or more conductors at one end of a cable for test purposes.

short message service (SMS) - Similar to e-mail store and forward, SMS is a service for sending short text messages (up to 160 characters) to mobile devices (phones, pagers) via SMS centers.

short wavelength (SW) - See wavelength.

shrouded dish - Used where interference to/from other systems on the same frequency and in the same area must be avoided.

sigma - The measurement of a process in producing defect-free design, product, delivery, and service, with a defect being anything that results in customer dissatisfaction.

signal encoding - The conversion of data into a form suitable for transmission over a medium.

signal fading - Parts of a signal branching into different paths from the transmitter to the receiver due to obstructions.

signal generator - Test equipment that generates a distinctive tone(s) that is placed on a cable pair for identification purposes. Also called a tone generator.

signaling - The central information or supervisory information provided by a network to facilitate circuit setup and disconnection. One example of signaling is the process used to transfer a sequence of bits over a communications medium.

signaling line circuit (SLC) - A circuit or path between any combination of circuit interfaces, control units, or transmitters over which multiple system input signals or output signals, or both, are carried.

Signaling System 7 (SS7) - A separate packet network that provides out-ofband signaling for the public switched telephone network.

signal quality error (SQE) - Transmission sent by a transceiver back to the controller to let the controller know whether the collision circuitry is functional. Also called a heartbeat. (Cisco Systems, Inc.)

signal splitters - Signal splitters are used to connect more than one antenna to a single radio.

signal strength - In a communications system, the signal power or intensity at a specified point and with respect to a specified reference level.

signal-to-noise ratio (SNR) - The ratio between the amount of signal power at the receiver input and the detected noise in a given communications system, expressed in decibels.

signature verification - A biometric method using a person's signature characteristics (writing speed, pen pressure, shape of loops, etc.) to identify that person.

simplex - A process during which signals are transmitted in only one direction; one station is the transmitter and the other is the receiver.

simplex signaling - A unidirectional signaling method in which data transfer can take place in only one direction, with no capabilities to change directions. See also dualduplex signaling, full-duplex signaling, and half-duplex signaling.

sine wave - A sinusoidal wave that varies periodically from zero to a maximum, back through zero to a minimum, and back to zero.

single attachment - A device in an optical fiber distributed data interface network that has a single transmit/receive connection to the primary ring.

single-attachment concentrator (SAC) - A fiber distributed data interface concentrator that has a single transmit/receive connection to the primary ring path only. Contrast with dual-attachment concentrator.

single-attachment station (SAS) - A fiber distributed data interface Class B station with a single transmit/receive connection to the primary ring path only. Contrast with dual-attachment station.

single-gang box - A device used to house information transport systems or electrical cabling for the purpose of attaching a faceplate or cover that houses connectors for the interconnection of equipment.

singlemode optical fiber - Optical fiber with a relatively small core diameter of 8-9 micron (micrometers) and a cladding diameter of 125 micron; lightwave propagation is restricted to a single path, or mode, in singlemode optical fiber.

single-point ground (SPG) terminal - A ground connecting point for connecting communications equipment and raceways to the building's grounding system.

single sideband modulation - A variation of the amplitude modulation technique where the carrier and one half of the sideband is suppressed. This effectively halves the bandwidth and power requirements of a radio frequency transmission.

single sign-on (SSO) - A system that makes it possible to store all identity information (e.g., various user names and passwords for each user and administrator) in a centralized database on the network.

site drawing - A two-dimensional graphic representation of the land and any exterior pathways that are being installed upon which a construction project will take place.

site survey - A process used to identify the characteristics of an environment impacting the installation of network components. Required for the design of any network.

skin effect - The tendency of current to flow only near the surface of a conductor. This effect becomes more pronounced at higher frequencies.

sky wave - A radio wave that travels upward from the antenna. A sky wave may be reflected to Earth by the ionosphere, troposphere, or stratosphere.

slab - See floor slab.

slab on grade - Concrete floor placed directly on soil, without a basement or crawl space.

stave - 1. A Bluetooth wireless device that communicates with a master to form a piconet. 2. Any secondary device that is controlled by a primary device, called the master.

sleeve - An opening, usually circular, through the wall, ceiling, or floor to allow the passage of cables.

slip sleeve - An oversized conduit that moves easily along an inner conduit and covers a gap or missing part of the smaller conduit.

Slot - An opening through a wall, floor, or ceiling, usually rectangular, to allow the passage of cables.

slotted antenna - A highly directional antenna. It utilizes slots in wave guides to radiate a signal in a single direction. It also can be used with solid conductors as a complementary dipole antenna.

slotted array - A type of very rigid antenna. Can be either fixed or rotating. It is used on aircraft, trains, radar, and cellular base stations.

slow frequency hopping - A frequencyhopping spread spectrum technique in which the frequency is changed once every 4.615 millisecond.

small computer system interface (SCSI) - A set of American National Standards Institute standard electronic interfaces that allows computers to communicate with peripheral hardware (e.g., disk drives, tape drives, CD-ROM drives, printers, scanners).

small form factor (SFF) connector - A connector that consists of two optical fibers secured in a plug approximately the size of an 8-position modular jack. An alternative type of optical fiber connector allowed under ANSI/TIA/EIA 568-B.3.

smart antenna - Combines multiple antenna elements with an active electronics signal processing capability to optimize and adapt the antenna pattern dynamically in response to the signal environment.

smart appliances - Products that include some processing power within themselves and have the ability to send or receive data or control messages to/from another product. All use some digital control to automate some product function and some send control messages, but most cannot both receive and send information.

smart card - A card with a built-in integrated circuit chip. This gives the card microprocessor memory and intelligence to use for storing data.

solar interference - Intense levels of direct sunlight that interfere with signal reception in free space optical systems.

solid conductor cable - A cable composed of a single gauge conductor wrapped in an insulating coating. Contrast with stranded conductor cable.

solid-state protector - Arc protection (arrestor) devices based on high-power semiconductor technology that do not deteriorate with age below a rated maximum surge current.

SONET node - See synchronous optical network (SONET) node.

sound level meter - Instrument used to measure actual pressure created by a sound.

sound pressure level (SPL) - The actual air pressure created by a sound as measured by a sound level meter.

source - The means (usually light-emitting diode or laser) used to convert an electrical information-carrying signal into a corresponding optical signal for transmission by an optical waveguide.

source address table (SAT) - The internal database used by a bridge to track the medium access control addresses of devices connected to each port of the bridge.

space (telecommunications) - An area used for housing the installation and termination of telecommunications equipment and cable.

space diversity - A wireless receiver configuration that utilizes two antennas located some distance apart in order to minimize the effects of certain types of fading (e.g., multipath). Since some types of fading are extremely localized, space diversity improves reliability because the second antenna may continue receiving the desired signal even when the first antenna is experiencing a fade.

smart environment - A smart environment employs pervasive embedded computation systems to collect sensory data from the real world, assess and evaluate the resulting information, interact with human users, and perform and facilitate alarm, decision-making, and control functions. Smart environments can exist in houses, vehicles, buildings, and campuses and include the use of communications networks, sensor devices, computer hardware, and software. The word "environment" refers to the location where the employed systems collect data and operate to adapt accordingly.

snake rod - A telescoping pole used to route horizontal cable above dropped ceilings.

sneak current - A foreign current flowing through terminal wiring and equipment that is driven by a voltage that is too low to cause the overvoltage protector to operate.

sneak current protection - The use of devices to protect against sneak currents either by interrupting the current (sneak current fuses) or grounding the conductor (heat coils).

socket - 1. A method of associating a program or process with a software address so they can communicate with other programs or processes. 2. A hardware defined socket connection is the combination of a data communication device address and the logical channel (port) number.

soft handoff - A cellular signal that is controlled by multiple cells before disconnecting and being handed off from the previous controlling cell (make-beforebreak).

softphone - Internet protocol telephone software installed on desktop, laptop, or handheld computers.

softwired - The type of power cord used to connect uninterruptible power supplies with plug-in type power receptacles.

space wave - A radio wave that is not reflected back to earth and continues into outer space. These radio waves above 30 MHz have shorter wavelengths, which penetrate the ionosphere and continue on into outer space. Also called direct waves.

spade lug - A U-shaped metal connector that is soldered or crimped to a wire, used for connection to a terminal post.

span - The length between two support points. In aerial plant, the span is the space between two poles or building connection points.

span guy - Guying installed across a span placed on straight pole lines to reinforce them against excess tension placed on them by severe weather conditions. Also called a line guy or pole-to-pole.

spanning tree - An operation used by bridges to create a logical topology that connects all of the bridge-equipped networks to be interlinked. It ensures that no path loops exist on the internetwork.

spanning tree algorithm (STA) - An algorithm used by bridges to create a logical topology that connects all of the bridgeequipped networks to be interlinked. It ensures that no path loops exist on the internetwork.

spatial, resolution - Setting on an optical time domain reflectometer to determine how close individual data points are spaced in time and distance.

speaker - A device that changes electrical signals into sounds.

specialized common carrier - A common carrier offering a limited type of service or serving a limited market.

specification - An essential technical requirement for items, materials, or services, including the procedures to be used to determine whether the requirement has been met.

spectral mask - A radio transmitter's radiated power confined to a band of frequencies through the use of a bandpass filter.

spectrum - A range of frequencies (electromagnetic, optical, and radio) that comprises a signal or defines a communications channel.

spike - An instantaneous surge of energy. spine cable tray Open tray with a central rigid spine with cable support ribs along the length at 90-degree angles.

splayed - Sloped, slanted, or spread outward. Splayed maintenance hole duct entrances are placed toward the outward sides of an entrance wall rather than placed in the center of the entrance wall.

splice - 1. A joining of conductors meant to be permanent. (TIA) 2. A device that joins conducting or transmitting media. See also straight splice.

splice (ground wire) - A method where ground wire is extended .byjoining together two or more separate sections by fusing or mechanical connectors.

splice bank - Placement of 25-pair modules in a symmetrically spaced configuration within a splice enclosure.

splice box - A box, located in a pathway run, intended to house a cable splice.

splice case - A metal or plastic housing with a semi-cylindrical cavity used in identical pairs to clamp around a cable splice to provide a closure.

splice closure - A device used to protect a splice. (TIA) See also splice case.

splice tray - A container used to organize and protect optical fiber splices, as well as a means for storing fiber slack.

splicing - The act of joining copper conductors or optical fiber strands.

splicing head - A section of a splicing rig that supports the crimp head. It can be either single or dual.

splicing rig - A specific manufacturer's tool kit for terminating modular connectors.

split grip - A wire mesh grip that is open on one side and, when attached to cable facilitates the physical support of cable.

split pair - Transposition of two conductors of separate pairs.

splitter - A network device that provides signals to a number of outputs, which are individually matched and isolated from each other. A passive device used to divide the signal into two or more outputs.

spoofing - 1. The interception, alteration, and retransmission of data in such a way as to mislead the recipient. 2. An attempt to gain access to an automated information system by posing as an authorized user.

spool - 1. A combination of hardware and software commonly used by print servers to redirect requests destined for a printer. 2. Cylindrical containers of cable. See cable reel. 3. A cylindrical guide, typically used for routing jumpers, cross-connects, and patch cords.

spooling - The use of secondary or auxiliary storage as a buffer to temporarily store data until it can be queued for processing (e.g., print spooling)

spread spectrum - A radio transmission technology that distributes the transmitted signal over multiple frequencies within the assigned frequency band to increase the overall immunity of the signal to noise and prevent message interception.

spreading ratio - The number of bits used in the chipping sequence to represent a message bit.

spurious emissions - Emission on a frequency or frequencies that are outside the necessary bandwidth and the level of that may be reduced without affecting the corresponding transmission of information.

spurious rejection - The ability of a receiver to reject emission on a frequency or frequencies which are outside the necessary bandwidth and the level of which may be reduced without affecting the corresponding transmission of information.

stackable hub - Multiple hubs that are in close proximity, capable of being connected to each other using a short length of specialized cable assembly, and functioning together as a single unit. See also hub.

staging area - An area at a job site where the bulk of the materials and tools is kept and distributed.

stand-alone cell - A wireless cell with a single access point and no connectivity to any other network.

standard - A collection of requirements that encompass properties of components and systems that are intended to ensure an accepted degree of functionality and longevity. (ATIS)

standard network interface (SNI) - A device that serves as a demarcation point between the local exchange carrier and the customer. Usually a modular jack with some type of mounting forthe modularjack.

standby monitor - A device on a token ring LAN that monitors the active monitor. Its function during normal ring operations is to verify that an active monitor is operating on the ring.

standing wave ratio - The ratio of the amplitude of a standing wave at an antinode to the amplitude at a node. A normalized measurement or calculation conducted in radio frequency systems useful for determining the amount of power reflected back to a source versus that delivered to the load.

star coupler - An optical component that allows emulation of a bus topology in an optical fiber system.

star topology - A network topology in which services are distributed from or through a central point.

start bit - A bit used in asynchronous communications to indicate the beginning of a character. See also stop bit.

star-wired ring - Physical star configured as a logical ring. Also called a collapsed ring through a hub that performs all appropriate routing operations.

stateful inspection - Firewall software processes used to identify suspicious network communications.

static dissipaters - This device is an array that dissipates static charges by providing a low resistance route for static ground charge to reach the atmosphere, thus preventing a buildup of the ground charge to the value necessary to trigger a strike.

static grounding wrist strap - A device used to dissipate the built-up static charge from an individual to the ground to avoid damaging sensitive circuits.

station - 1. A device used by an individual to access network services. 2. An input or output point in a communications system (e.g., telephone, computer, fire alarm station). See also local station and remote station.

station cabling - See horizontal cabling.

station conductor - A wire that tetminates at the equipment side of the protector.

station cord - See work area cable (cord).

station equipment - See customer premises equipment and work station.

station fuse - An overcurrent device used at the customer's premises.

station location - Telephone or computer location.

steerablelpolar mount - Antenna support structure that steers the reflector.

step by step (SxS) - An electromechanical telephone switching system.

step-index fiber - An optical fiber, either multimode or singlemode, in which the core refractive index is uniform throughout so that a sharp step in refractive index occurs at the core-to-cladding interface.

stick - Slang term used to describe a section of conduit.

stipulated sum - See lump sum.

stop bit - A bit used in asynchronous communications to indicate the end of a character. See also start bit.

storage area network (SAN) - A specialized high-speed network dedicated to the transport of data between storage devices and servers.

storage virtualization - See virtualization.

store-and-forward - 1. The recording, processing, storage, transmission, and viewing of an activity after it has occurred. Contrast with real-time. 2. A switching method in which messages are stored as they are received, fully checked for errors, and then forwarded. See also cut-through and modified cutthrough.

STP-A - An IBM designed, shielded twistedpair cable consisting of two individually shielded 22 AWG [0.64 mm (0.025 in)] conductor pairs, with an overall shield capable of supporting transmission to 300 MHz.

straight splice - A splice in which one conductor or optical fiber strand is spliced from opposite directions.

straight tip (ST) connector - A type of optical fiber connector identified by its bayonet mating mechanism. Also called BFOC/2.5 (bayonet fiber optic connector with 2.5 mm [0.10 in] ferrule).

strand - 1. A single string of wire used to make up a larger wire or cable by twisting a number of strands together. Galvanized steel stranded cable is used as support strand and guy wire. 2. A single unit of optical fiber within a cable.

stranded cable - A cable with individual conductors composed of groups of wires twisted together.

stranded conductor cable - A cable composed of a bundle of smaller gauge wires wrapped in a single insulating coating. Contrast with solid conductor cable.

strand identifier - A clamp-on unit that inserts a microbend into optical fiber cable and detects light escaping from the fiber.

strand vise - A gripping device used with a hoist for the tensioning of a strand.

streaming - A group of technologies developed to enable the transfer of multimedia content over a network for immediate play at the receiving device before the entire file has been downloaded.

strength member - That part of an optical fiber cable composed of aramid yarn, steel strands, fiberglass filaments, or fiberglass-reinforced epoxy composite rod that increases the tensile strength of the cable.

stress detector - A device that detects the stress in beams when walking above or near.the detector.

striping - A data storage technique in which the content of a given file to be stored is divided and placed on multiple hard disk drives for faster retrieval and improved fault tolerance.

stripping in token ring - The process of a sending device removing the frames it has previously transmitted from the ring.

stroke factor - The number of lightning strokes to ground per unit area for each thunderstorm day (obtained by statistical studies).

structural return loss (SRL) - Ratio in dB of the test signal power and the reflected signal power due to impedance variations in the cable.

structured cabling system (SCS) - The complete collective configuration of telecommunications cabling and associated hardware at a given location. stub-out See conduit stub-out. stub-up See conduit stub-u

subbase - A layer of specified material between the pavement and the subgrade.

subduct - See innerduct.

submittal - Information, documentation, or samples that a contractor may be requested to submit to the design team for review and approval before the commencement of work.

subnet - See subnetwork.

subnet mask - A fictitious (nonusable) Internet protocol (IP) address whose only function is to identify the number of bits, within a 32 bit IP address field, that have been borrowed from the host address to identify a subnet. This mask is used by Layer 3 devices to identify subnets.

subnetting - The process of dividing a single broadcast domain into two or more smaller broadcast domains by modifying Network layer address assignments. See also subnetwork.

subnetwork - A single broadcast domain in a network that is made up of multiple broadcast domains.

subscriber connector (SC) - The optical fiber SC connector (SCFOC/2.5) has a square front profile with push-pull latching mechanism maintaining the polarity of duplex cables.

subscriber identity module (SIM) card - A smart card inserted into the Global System for Mobile Communications mobile station containing customer information.

subscriber line - A communications channel from a switching center or an individual message distribution point to the user terminal.

subscription limit - The number of users that a network is designated to economically accommodate, under normal operating conditions, without degrading network services.

substitution - A replacement or alternation of material or process called for in the design documents.

superhigh frequency (SHF) - Frequencies in the range of 3 GHz to 30 GHz

supernetting - The combining of two separate but contiguous Class C Internet protocol networks into a larger group connected to a single, common interface (generally a routing device).

supervisory control and data acquisition (SCADA) - SCADA systems are used in industry and by public utilities (e.g., pipelines, electric utility grids) to monitor and control plant status and provide logging facilities that are often scattered over wide geographic areas. SCADA systems are highly configurable and traditionally use standard telephone lines to propagate their data. Public utilities are starting to utilize these systems for the integration and transmission of voice, data, and security systems.

supplementary - The way to provide additional conditions to a contract that may add, delete, or modify the general conditions.

support strand (messenger) - A strength element used to carry the weight of the telecommunications cable.

surety bond - A bond that ensures a respondent (bidder) to a request for quote (RFQ) is sincerely interested in performing the project and has responded accurately to the RFQ specifications.

surf control - A security process used to prevent internal network users from accessing unauthorized Web sites. Also called Internet access management.

surface fitting - Surface-mounted service fitting. See also service fitting.

surface-mounted raceway - Plastic or metallic raceway that is installed on the surface of a wall, floor, or ceiling that provides a protective pathway for cables and/or power from public access.

surge arrester - 1. A protective device for limiting surge voltages by discharging or bypassing surge current, and it also prevents continued flow of follow current while remaining capable of repeating these functions. (NEC) 2. Electrical or lightning arrestors designed to protect equipment between the power source and the equipment being protected.

surge protective device - See surge arrester.

survivability - The ability of the network to function after minor or major disruption.

susceptibility (electromagnetic) - The inability of a device, equipment, or system to resist an electromagnetic disturbance.

suspended ceiling - A ceiling that creates an area or space between the ceiling material and the structure above.

sweep test - A measurement performed where a range of signals of different frequencies are injected into a radio frequency system in order to measure the resulting performance.

sweep - Bend that has a gentle arc rather than a sharp bend.

swell - An increase in the nominal root mean square voltage or current lasting from 0.5 cycles to one minute.

swing floor phasing - The act of removing personnel and property from one location to another in order to facilitate renovation of the space vacated.

swingset - See bullwheel.

switch - 1. A network access device that provides a centralized point for LAN communications, media connections, and management activities where each switch port represents a separate communications channel. Sometimes referred to as a multiport bridge. See also bridge. 2. A voice communications device that utilizes switching technology to establish and terminate calls.

switch fabric - Multiple switches used to link storage area network storage devices to server clusters.

switch latency - The amount of time it takes for an incoming message to be inspected, processed, and forwarded through a switch.

switch matrix - Connections that link each port to every other port. Also called a backplane.

switched virtual circuit (SVC) - A virtual circuit created on an as-needed basis. It is a temporary connection lasting only as long as the connected devices are communicating. Contrast with permanent virtual circuit.

switching - 1. Networking protocol in which a station sends a message to a hub, which then routes the message to the specified destination station. 2. Establishing a direct signal path from one device to another.

symmetric key cryptography - See private key encryption.

symmetrical pair - A balanced transmission line, in a multipair cable, having equal conductor resistances per unit length, equal impedances from each conductor to earth, and equal impedances to other lines.

synchronization profile - Commonly used in a personal area network to update calendar and scheduling information between laptop, personal digital assistant (PDA), and mobile phone. Once the PDA device comes within range, the synchronization can automatically occur.

synchronous communication - See synchronous signaling.

synchronous connection oriented (SCO) link - A point-to-point link between the master device and one slave device, used primarily for synchronous voice traffic.

synchronous optical network (SONET) node - The interface to a SONET network.

synchronous optical (SONET) - A scalable transport technology designed to provide a uniform, consistent method of transferring data, by using an optical fiber transmission infrastructure network.

synchronous signaling - A form of signaling in which no start and stop bits are used. Each data character is coded as a string of bits and the sending and receiving devices are synchronized with each other, using a common clock. See also asynchronous signaling and isochronous signaling.

synchronous transmission - Transfer of data using synchronous signaling.

system integrity - That condition of a system wherein its mandated operational and technical parameters are within the prescribed limits.

system reliability - The probability that a system, including all hardware, firmware, and software, will satisfactorily perform the task for which it was designed or intended, for a specified time and in a specified environment.

T1 (DS 1) - The digital transmission link consisting of 24 channels to support rates of 1.54 Mb/s.

T3 (DS 3) - The digital transmission link consisting of 672 channels to support rates of 43 Mb/s, each channel supporting 64 kb/s.

tagging - The marking of a message for the purpose of specialized processing or handling on a LAN or internetwork.

tailgating - See piggybacking.

tap - 1. An electrical connection permitting signals to be transmitted onto or off a bus. 2. The linking between the bus and the drop cable that connects the workstation to the bus in 10BASE-5 Ethernet. 3. A device used on community antenna television cables for matching impedance or connecting service drops. See also bridged tap.

taper point - A splice location where the cable size along a route is reduced.

tap-off - See tap.

tapped trunk - A cable connection system where a coaxial cable is tapped by means of a splitter or vampire tap.

teaming - See link aggregation.

telecom hotel - A building that is leased or rented by multiple telecommunications service providers. The building is generally equipped with specialized environmental and power conditioning.

telecommunications - Any transmission, emission, and reception of signs, signals, writings, images, and sounds; that is, information of any nature by cable, radio, optical, or other electromagnetic systems.

telecommunications bonding backbone (TBB) - A copper conductor used to connect the telecommunications main grounding busbar (TMGB) to the telecommunications grounding busbar (TGB) located on the floor farthest away.

telecommunications bonding backbone interconnecting bonding conductor (TBBIBC) - See grounding equalizer.

telecommunications bonding jumper - See bonding conductor for telecommunications.

telecommunications circuit - Links that make it possible for an organizational network to grow beyond the physical boundaries of a building or a campus.

telecommunications closet (TC) - See telecommunications room.

telecommunications drawing - A two dimensional graphic representation of the cabling infrastructure elements for a construction project (e.g., pathways, media types and quantities, work area outlets, telecommunications rooms).

telecommunications enclosure (TE) - 1. A case or housing for telecommunications equipment, cable terminations, and cross-connect cabling. (TIA). 2. A telecommunications space that differs from equipment rooms and entrance facilities in that this space is generally considered a floor-serving or tenant-serving (as opposed to building- or campus-serving) space that provides a connection point between backbone and horizontal cabling.

telecommunications entrance facility (TEF) - See entrance facility (telecommunications).

telecommunications entrance point - See entrance point (telecommunications).

telecommunications entrance room or space - See entrance room or space (telecommunications).

telecommunications equipment bonding conductor (TEBC) - Bonding conductor that should be installed from each piece of equipment in the telecommunications room or equipment room to the telecommunications grounding busbar or telecommunications main grounding busbar.

telecommunications equipment room - See equipment room (telecommunications).

telecommunications grounding busbar (TGB) - A common point of connection for telecommunications system and equipment bonding to ground, and located in the telecommunications room or equipment room.

telecommunications infrastructure - See infrastructure (telecommunications).

telecommunications main grounding busbar (TMGB) - A busbar placed in a convenient and accessible location and bonded, by means of the bonding conductor for telecommunications, to the building service equipment (power) ground.

telecommunications media - See media (telecommunications).

telecommunications outlet (TO) - See outlet/connector (telecommunications).

telecommunications outlet/connector - Provides the means for the tenant to connect premises equipment. See also outlet/connector (telecommunications).

telecommunications room (TR) - An enclosed architectural space for housing telecommunications equipment, cable terminations, and cross-connect cabling.

telecommunications service entrance - See entrance facility (telecommunications).

telecommunications space - See space (telecommunications).

Telecommunications Systems Bulletin (TSB) - Document published bytheTelecommunications Industry Association used to provide guidance for design methodologies or installation practices that pertain to telecommunications cabling systems. The next published edition of a related standard typically incorporates these bulletins.

telecommuting - The practice of connecting a remote network device to the organizational network to allow staff to work away from the office.

teleconference - The live exchange of information among persons and machines remote from one another but linked by a telecommunications system.

telemetry - A communications system designed for the automatic transmission of digital or analog data by wire, radio, or other means from remote sources to a receiving source for the recording, monitoring, and analysis of systems.

telephone backboard - An area used for the purpose of cable termination and cross-connection of telecommunications circuits. May be used for cross-connection or interconnection to active equipment or simply as a cross-connection of backbone cabling.

telephone test set - A voice circuit testing device used to identify circuits and perform diagnostics (e.g., butt set).

telephony - 1. Speech transmission by radio sets or telephone sets. 2. Describing telephone equipment and telephone technology.

telescoping pole - A pole used for lifting and moving cable in open ceilings.

temporary cabling - Cables and equipment that are installed to provide service on a temporary basis.

tensile strength - The longitudinal pulling stress needed to break apart a cable or material.

terbo - A suffix that denotes a third version.

terminal (TERM) - 1. A point at which information may enter or leave a telecommunications network. (TIA) 2. A device by means of which wires may be connected to each other.

terminal block (TB) - A protected or unprotected unit that serves to terminate cable conductors and is a transition point between cable conductors.

terminal emulation - The process that enables a personal computer to operate as a terminal for connecting to a mainframe or minicomputer.

terminal mode - A form of remote access where the remote station accesses LAN resources through a specialized terminal server, which makes all requests for LAN resources on behalf of the remote station. Contrast with browser mode, control mode, and transparent mode.

termination - The ending of a transmission or transmission pathway.

termination hardware - Considered to be obsolete. See also connecting hardware.

termination position - A discrete element of connecting hardware where telecommunications conductors are terminated.

terminator - An impedance-matching device placed at the end of the telecommunications transmission line.

terms and conditions (T&C) - A section in a request for quote (RFQ) that defines the terms used in the RFQ and the conditions under which the work must be performed.

test hole - A hale or group of holes dug along a proposed underground route to determine what utilities or other obstructions may be present.

tetrafluoroethylene (TFE) - A thermoplastic material with good electrical insulating properties and chemical and heat resistance.

thimble eye - A device for securing the end of a strand.

thimble eye rod - A device used to place the guy wire(s) within the eye opening when guying from a main pole to a stub pole or when guying to the ground. Also called a thimble eye bolt.

thin client - A device similar to a personal computer with respect to processing power, memory capacity, and graphics capability but lacking removable storage devices.

third generation (3G) mobile telephony - A wireless system intended to provide a global mobility with services including telephony, paging, messaging, Internet, and broadband data. This system provides high-speed data transmissions from 144 kbls to 2 Mb/s. 3G will support multimedia applications (e.g., full-motion video, video conferencing).

threadless fitting - A conduit connector or coupling that does not thread onto the end of the conduit. The compression ring style provides a weatherproof seal.

threat analysis - An evaluation of an environment, structure, or scenario for the purpose of deterring potential vulnerabilities for unauthorized entry, removal of physical or intellectual material, or exposure to terrorist activities.

through penetration - A continuous opening that passes through both surfaces of a fire-rated barrier.

throughput - The amount of data transferred between two points in a given amount of time.

through-window - Refers to transmitting and receiving free space optics signal through glass.

thunderstorm day - Any day thunder is heard at a specific observation point.

tie wrap - Plastic or hook and loop strip used for binding and dressing cable.

tight buffer - A type of cable construction where each fiber is coated with a protective thermoplastic coating to a diameter of 900 microns.

tilt compensator - A variable controlled device used to correct imbalances in video signals.

time division duplex (TDD) - A radio frequency communication scheme that transmits and receives alternately with sequential time slots using a single frequency.

time division multiplexing (TDM) - A transmission technique whereby several low-speed channels are combined into a single high-speed channel for transmission. Each low-speed channel is allocated a specific time position in the bit stream.

time division synchronous code division multiple access (TD-SCDMA) - A third generation mobile telephony standard being developed by the China Academy of Telecommunications Technology in collaboration with Datang and Siemens.

time domain reflectometer (TDR) - A device that sends a signal down a cable, then measures the magnitude and amount of time required for the reflection of that signal to return. TDRs are used to measure the length of cables as well as locate cable faults.

time zone - A specified period of time in which access is allowed.

tip - A means for identification of one conductor of a pair. Historically, associated with the wire connected to the tip portion of an operator's telephone plug. See also ring.

token - A Layer 2 frame containing access control information that is passed from device to device on a token ring, bus, or fiber distributed data interface network.

token bus - An access control method that requires a device to have a token before transmitting its message. Transmissions are in the form of broadcasts that are received by all other devices connected to the network over a logical bus topology.

token passing - An access control method that uses an electronic signal called a token.

token ring - A network protocol in which attached devices share a common cabling system for communications purposes without the possibility of a collision between transmissions. A device is only able to send a message when it is in possession of a special electronic sequence of bits called a token.

tone generator - 1. A device used to apply an analog signal to an electrical conductor for assistance in its identification or to determine its physical or fault location. 2. A device used to generate distinctive audible sounds (tones) for insertion into audio, paging, and telephone systems.

tone probe - A device used to detect an electrically generated signal applied to a cable by a tone generator to assist in identification or fault location. See also tone generator.

top-down design - See functional design process.

topology - The physical or logical arrangement of a telecommunications system. (TIA) See also logical topology and physical topology.

total internal reflection - Confinement of light within an optical fiber because the angle of incidence is within the numerical aperture.

trade size - Name given to materials to identify a nominal size.

traffic prioritization - See prioritization.

traffic shaping - A technique that directs data streams on the basis of their address, protocol, priority, or application content.

trailer - An ending component found in some data packets or frames.

trailer string - Line attached to the end of a cable(s) being pulled. May be used for future additional pulls.

transactional access - The process of providing remote users the means to connect to a LAN to conduct commercial activities. See also content access and resource access.

transceiver - 1. A radio transmitter and receiver combined into a single unit. 2. A device that acts as an interface between the network and the connected device.

transcoding - The process that converts a data transmission between different types of codecs (G.711, G.726, G.729, etc.). This process is used for traditional video conferencing and for video over Internet protocol.

transducer - 1. A specific type of converter (see converter) that changes one form of energy into another. 2. In pressurized systems, a device that permits reading the cable pressure in a pressurized cable.

transfer impedance - A measure of shielding performance determined by the ratio of the voltage on the conductors enclosed by a shield to the surface currents on the outside of the shield.

transition point - 1. A point at the bottom of a wall where a flat undercarpet cable is transitioned to a round unshielded twisted-pair cable. 2. A point where an unlisted cable is transitioned to a listed cable after entering a building.

translational bridge - A networking device capable of converting frame formats from one type to another prior to forwarding messages. Only operates on the logical link control sublayer of the Data Link layer.

translational repeater - A type of repeater used in wireless communications. Translational repeaters regenerate a signal received on one frequency or channel and then retransmit it on another frequency or channel. See also repeater and transponder.

transmission - The movement of information as electrical or optical signals from one point to another via a medium.

transmission budget - The calculated limit for quality service available based on transmission characteristics.

Transmission Control Protocol (TCP) - An Open Systems Interconnection Reference Model Layer 4 connection-oriented protocol. TCP supports reliable, end-toend transmission of data by allowing for guaranteed delivery and sequencing of packets. See also User Datagram Protocol for contrast.

transmission line - A medium used to transport a desired signal between two points.

transmission loss - The decrease in signal that occurs during transmission from one point to another. Expressed in dB.

transmission media - The physical carriers of signal energy radiation (e.g., copper, optical fiber, air). See also media.

transmission medium - See media.

transmission speed - The rate of flow (speed) of binary digit information over a transmission line, expressed in bits per second.

transmit opportunity (TXOP) - Provides a channel access function controlled with a defined starting time and a maximum duration. Access may be obtained by contention or through polling.

transmitter (TX) - Signaling source.

transmitter combiners - A device that allows several transmitters operating in the same frequency range to use a single transmission line and antenna.

transparent bridge - A bridge used in an environment where all ports use the same LAN technology.

transparent mode - A form of remote access where the remote station accesses LAN resources through a remote access server and operates in the same manner as a local station, eliminating the need for a local station.

transponder - 1. A combination uplink receiver and downlink transmitter acting like a repeater. 2. A wireless passive or active communications device that automatically responds to signals picked up.

Transport layer - The Open Systems Interconnection Reference Model layer responsible for providing a level of quality to the message transfer process. Also called Layer 4.

transposed pairs - When two pairs of conductors are terminated in each other's location.

transverse - Lying or extending across or in a cross direction. To pass over, under, or through.

trapeze - A support device using threaded rod and channel stock.

traverse - See transverse.

tree topology - A LAN topology that has only one route between any two nodes on the network. The pattern of connections resembles a tree, or the letter T.

trench duct - An interior or exterior trough embedded in concrete that has removable cover plates level with the top of the surrounding surface. See also header duct.

tri-bit - Three bits; three binary digits.

trim-out - Usually one of the last steps in the home construction process, this is the period when all cables are terminated to the appropriate devices and testing is completed.

triple data encryption standard (3DES) - A version of the data encryption standard using 64 bit keys to encrypt the text message three times using different keys each time.

tri-shielded - A general description for one type of broadband coaxial cable that uses three separate shields under the dielectric outer cable sheath. This type of cable construction is typically used with 75 ohm coaxial cabling.

trough (cable) - A pathway for the containment and protection of cable, typically provided with a removable cover.

trunk cable - Refers to the main distribution cable. A typical trunk cable begins at the headend and terminates at the outermost feeder cable.

trunk coupling unit (TCU) - A unit used to connect a token ring device to the main ring path. It provides the mechanisms for connecting a device to the ring and removing it from the ring in an orderly manner. More commonly called a port.

trunk distribution and feeder - Rigid coaxial cable, typically used for backbone cabling.

trunking - See link aggregation.

T-tap - A device that attaches to a medium used for the purpose of connection to a circuit.

tugger - Device that acts as an assist mechanism for advancing a cable or groups of cables during installation.

tunnel - A virtual private network connection through the Internet.

turnstile - An entryway that uses a mechanical device to restrict entry to one person at a time.

twinaxial - A type of cable described as having two conductors that are insulated from one another, twisted together, surrounded by a common shield, and protected with an outer thermoplastic jacket.

twisted-pair - Two individually insulated copper wires physically twisted together to form a balanced pair.

twisted-pair cable - A multiconductor cable comprising two or more copper conductors twisted in a manner designed to cancel electrical interference. Also called balanced twisted-pair cable.

Twisted-Pair Physical Medium Dependent (TP-PMD) - A network protocol that allows for 100 Mb/s transmission. Another name for ANSI X3.263 standard and copper distributed data interface.

two-level duct - An underfloor raceway system installed with the header raceways and the distribution raceways on two different planes.

two-point method - A method used to measure optical fiber cable loss utilizing two closely spaced cursors on an optical time domain reflectometer.

Ufer grounding - Steel reinforcement is used in place of copper wire ground due to the pH factor of concrete.

ultrahigh frequency (UHF) - Frequencies in the range of 300 MHz to 3000 MHz.

ultraviolet (UV) light - The portion of the electromagnetic spectrum in which the longest wavelength is just below the visible spectrum, extending from approximately 10 nm to approximately 400 rim.

Um - A global system for mobile telephony air interface component or radio link.

unauthorized access - In general, the use of any network resource without approval as established in the security policy.

unbalanced cable (circuit) - A cable (circuit) that is not equal in phase and opposite in magnitude (e.g., coaxial cables are unbalanced). Contrast with balanced twisted-pair cable.

unbounded medium - A term sometimes used to describe wireless. Contrast with bounded medium.

underfloor raceway - A pathway placed within the floor and from which wires and cables emerge to a specific floor area.

underground - Refers to conduit and maintenance hole systems installed below the surface of the ground.

underground cable - A telecommunications cable designed to be installed under the surface of the earth in a trough or duct that isolates the cable from direct contact with the soil. (T!A) Contrast with directburied cable.

underground entrance - Entrance facility using conduit or other types of mechanical pathways to provide out-of-sight service to a building.

unequal splitter - A device that asymmetrically splits a radio frequency signal between two outputs while maintaining dc continuity between all ports.

unicast - A technique for sending data to a single network device. A one-to-one mode of communication. See also broadcast and multicast.

unidirectional antenna - An antenna characterized by a very narrow focus and an extended reach. See directional antenna and omnidirectional antenna.

unidirectional signaling - Signaling that occurs in one direction. Contrast with bidirectional signaling.

UniFormat - A document produced by the Constructions Specifications Institute that is a classification system used to organize preliminary project descriptions, preliminary cost estimates, and drawings that detail filing.

unigrounded power system - A power system where only one point, usually the midpoint, of the supply transformer bank is grounded. The neutral conductor may or may not be carried along with the phase wires.

unintentional radiators - A device that intentionally generates radio frequency energy for use within the device or that sends radio frequency signals by conduction to associated equipment via connecting wiring, but which is not intended to emit radio frequency energy by radiation or induction.

uninterruptible power supply (UPS) - A device that is inserted between a primary power source and the primary power input of equipment to be protected to eliminate the effects of transient anomalies or temporary outages.

unistrut - See channel stock.

universal mobile telecommunications service (UMTS) - A third generation broadband, packet-based transmission of text, digitized voice, video, and multimedia at data rates up to 2 Mb/s, similar to wideband code division multiple access.

unknown user - All individuals who do not have existing identity profiles on the network they are attempting to access.

unlicensed frequency band - Radio frequencies that require no license. The unlicensed frequency requirements vary by country.

unlicensed multipoint - A radio system linking three or more nodes that does not require formal government license to install and operate (i.e., spread spectrum radio).

unlicensed national information infrastructure (U-NII) - Designated to provide short-range, high-speed wireless networking communication at low cost. Consists of three frequency bands in the 5 GHz band of 100 MHz each: 5.15 to 5.25 GHz, 5.25 to 5.35 GHz and 5.725 to 5.825 GHz.

unprotected system - A nonredundant wireless system that uses a single transceiver and antenna.

unshielded twisted-pair (UTP) cable - Cable made up of one or more pairs of twisted copper conductors with no metallic shielding. The entire assembly is covered with an insulating sheath (cable jacket).

unshifted singlemode - See dispersion unshifted.

unsoldered mechanical (UM) protection - Additional steel and polyethylene sheaths provided over the inner polyethylene cable jacket.

unusable floor space - Floor space that is typically used in support of the building occupants (e.g., core area, mechanical/ electrical rooms, hallways) but does not allow for occupancy of building tenants. Contrast with usable floor space.

uplink - 1. Signals transmitted from ground stations to satellites. 2. In demand priority access method, the communications channel between a connected end node and a repeater, or between a repeater and a higher-level repeater.

upload - To send information from the controller to the host computer.

upstream neighbor's address (UNA) - In token ring, the address of the device immediately preceding a given device on the ring communications path.

uptime - The time during which a functional unit is fully operational.

urban wire - Multiconductor cable, 19 AWG [0.91 mm (0.036 in)] or 22 AWG [0.64 mm (0.025 in)], with a center strand and no outer sheath.

usable floor space - Floor space that is capable of being used as a work area. (TIA) Contrast with unusable floor space.

user code - A unique designation assigned to a person who is expected to use the circuit, equipment, service, etc., serving a particular work area.

User Datagram Protocol (UDP) - An Open Systems Interconnection Reference Model Layer 4 connectionless protocol that is part of the Transmission Control Protocol (TCP)/Internet Protocol suite. UDP supports single packet data transmission with no guarantee of message delivery. See also Transmission Control Protocol (TCP) for contrast.

utility column - An enclosed pathway extending from the ceiling to furniture or to the floor that forms a pathway for electrical wiring, telecommunications cable, or both.

utility pole - A customer-owned outside plant pole owned by a private or municipal utility. See also pole.

utility tunnel - An enclosed passageway, usually placed between buildings, for the distribution of utility services.

value engineering - An effort to examine and weigh the initial cost; evaluate the maintenance expense and ultimate worth of certain materials, components, and systems; and assess performance at the lowest price consistent with the project criteria during the design development/ preliminary design phase.

valve-regulated lead-acid (VRLA) cell - A battery cell that is regulated by a pressure relief valve and does not allow for the adding of water. Also called sealed or maintenance-free cells.

vampire tap - A device used to provide an electrical connection to a transceiver into thick Ethernet cable without breaking/cutting the cable.

variable air volume (VAV) - A self-contained heating, ventilating, and air-conditioning (HVAC) unit that uses a built-in microprocessor-based controller to control environmental air to a specific zone via a damper. The unit is placed near the end of a HVAC duct and can also monitor temperature inputs from local sensors.

varistor - An electrical component whose resistance depends on the applied voltage or current.

vault - A telecommunications space, typically subterranean, located within or between buildings and used for the distribution, splicing, and termination of cabling. These spaces may be established as a maintenance hole in campus environments or they may include active equipment in addition to passive cabling such as in a controlled environment vault.

velocity of propagation - The speed of transmission along a cable relative to the speed of light in a vacuum.

ventilated channel - Channel section with a one-piece bottom no more than 150 mm (6.0 in) wide.

ventilated trough - A ventilated bottom with side rails.

vertical down lead (VDL) - A ground wire placed on a pole that leads down to the ground electrode at the base of the pole.

vertical spiral - An omnidirectional vertical log-periodic antenna may be formed using a continuous spiral with the radius and spacing of each turn varying in the same manner as the dipole array relationship. Such an antenna must be operated over a ground plane and fed unbalanced.

very high frequency (VHF) - Frequencies from 30 MHz to 300 MHz.

very low frequency (VLF) - Frequencies from 3 kHz to 30 kHz.

V-groove - Position in fusion splicer where optical fiber strand is placed.

vibration resistance - The ability of an antenna to mechanically survive the flexing and vibration caused by wind blowing across it and its supporting structure.

vibration spacer - A material placed between conduits and support iron used to cushion a conduit run attached to bridges from the vibrational stress associated with moving traffic loads on the bridge structure.

Vigants formula - 1. An equation that models performance factors used when providing space diversity to an unprotected system. 2. An equation that models rain outages of radio frequency systems.

vignetting - A tunnel or porthole image that is produced by using a smaller image-size format lens on a larger image-size format camera (i.e., 8.3 mm lens and 13 mm camera). Similar to an unbordered picture, often a portrait, that shades off into the surrounding color at the edges. Conversely, one can use a larger image-size lens on a smaller image-size format camera.

virtual circuit (VC) - A communications path through an internetwork that appears to be a dedicated circuit between two network devices.

virtual LAN (VLAN) - A technique made possible by switching technologies that permits the logical grouping of any number of network devices into one or more subnetworks to improve traffic management and/or security.

virtual private network (VPN) - A combination of hardware and software technologies designed to enable secure passage of organizational network traffic over the Internet. See also tunnel.

virtualization - The software and procedures that make it possible for users and administrators to view and manage a group of storage devices as a single unit regardless of differences in capacities, locations, and device types.

visible light - The frequency range of light that is detectible by the human eye. The frequency (wavelength) range is from 390 nm to 780 rim.

visual fault locator (VFL) - Small handheld visible light source consisting of a light emitting diode, lamp, or visible laser. Used to identify optical fibers, faulty connectors, or optical fiber breaks. See hot red light.

voice band - An analog voice circuit that transmits signals in a frequency band of 300-3400 Hz.

voice frequency (VF) - Pertaining to those frequencies within the part of the audio range that is used for the transmission of speech.

voice grade (VG) - AnyLAN A hub-based LAN using demand priority access method technology (IEEE 802.12) that can transport token ring or Ethernet frames at a transfer rate of 100 Mb/s.

voice over Internet prbtocol (VoIP) - A system in which voice signals are converted to packets and transmitted over a network using Transmission Control Protocol/Internet Protocol.

voice recognition - Identifying an individual by comparing previously stored voice recordings key words or phrases with the same key phrases spoken at the same time access is requested.

volt (V) - A unit of electromotive force or potential difference that will cause a current of one ampere to flow through a resistance of one ohm.

voltage - Electrical potential or potential difference expressed in volts.

voltage gradient - The change in voltage differential per unit distance. See also electric field strength.

voltage standing wave ratio (VSWR) - The ratio of the maximum to the minimum voltage in the standing wave pattern that appears along a transmission line.

voltage standing wave ratio (VSWR) protection - A device that measures the level of undesirable reverse power caused by impedance mismatches between a radio frequency (RF) transmitter, its transmission line, and the antenna. The measuring and limiting reverse RF power will prevent damage of these components.

volt-ohmmeter (VOM) - An instrument used to measure electrical characteristics. See multimeter.

volume control - A device used to increase and decrease the audio level of a speaker(s).

wall mount bracket - Support device having a diagonal brace between the vertical section and the horizontal section, and mounted to a wall.

Walsh code - A common orthogonal code used for direct sequence spread spectrum in a code division multiple access network.

waveguide - A device used to direct radio frequency transmissions or light waves. A waveguide in radio systems normally consists of a hollow metallic conductor, usually rectangular, elliptical, or circular in cross section. In lightwave applications, a waveguide is normally small prisms or optical fibers.

wavelength - The distance between two points in the same phase in consecutive cycles measured in the direction of propagation.

waveshape (lightning) - The numerical method of describing a voltage surge wave in terms of rise time versus decay time (e.g., 1 x 50 or 10 x 100). The first number represents the rise time of the surge in microseconds from zero to peak surge value. The second number represents the subsequent surge decay time to 50 percent of the peak surge value from the beginning of the surge.

wayside - A channel on a microwave carrier that can accommodate small amounts of traffic without requiring multiplexers at each site.

Web site acceleration - A term used to describe a content acceleration appliance that is used to cache the locally stored content requested by remote users. Also called reverse proxy. See also Internet acceleration.

whip antenna - A long, thinly shaped omnidirectional antenna.

wide area interface card (WIC) - See remote access interface card.

wide area internetworking - See wide area network.

wide area network (WAN) - A data communications system that uses telecommunications circuits to link LANs that are distributed over large geographic distances.

wideband - The property of a circuit that has a bandwidth wider than normal for the type of circuit, frequency of operation, or type of modulation.

wavelength division multiplexing (WDM) - Developed to increase the information-carrying capacity of optical fiber transmission systems. This technique modulates a series of data streams using a different wavelength of light for each stream and simultaneously transports the multiple wavelengths over a single optical fiber.

wideband code division multiple access (WCDMA) - A channel that is four times wider than the current channels typically used in second-generation networks in North America.

winch - A device that acts as an assist mechanism for advancing a cable or groups of cables during installation.

wind load - The total force exerted by the wind on a structure or part of a structure. The total design wind load includes the sum of the horizontal forces applied to the structure in the direction of the wind and the design wind load.

window attenuation - In free space optics systems, clear glass windows introduce approximately four percent attenuation for each pane of glass traversed by a beam. Tinted or coated windows, however, can cause much greater attenuation of the optical beam.

wire - An individually insulated solid or stranded metallic conductor.

wired equivalent privacy (WEP) - WEP data encryption is defined by the IEEE 802.11 standard to prevent (a) access to the network by intruders using similar wireless LAN (WLAN) equipment and (b) capture of WLAN traffic through eavesdropping. Access is denied by anyone who does not have an assigned key.

wireless access reconnaissance (WAR) driving - A process of traveling and looking for wireless access point signals that can be used to acquire network access.

wireless fidelity (Wi-Fi) - when referring to IEEE 802.11 blg equipment, a trade term promulgated by the WiFi Alliance. Wi-Fi is used in place of IEEE 802.11 b/g in the same way that Ethernet is used in place of IEEE 802.3.

wireless LAN gateway - A device that provides functions similar to a wireless LAN switch but with additional administrative features.

wireless LAN switch - A network access device designed to centrally manage all connected access points in a wireless LAN environment.

wireless local area network (WLAN) - Using radio frequency technology, such networks transmit and receive data over the air, minimizing the need for wired connections. Thus, WLANs combine data connectivity with user mobility. WLANs are essentially networks that allow the transmission of data and the ability to share resources (e.g., printers) without the need to physically connect each node, or computer.

wireless mesh network (IEEE 802.11x) - network that uses a mesh network topology between wireless nodes.

wire management - Components placed on racks or walls to support the routing of cables.

wire map - Pin to pin termination and continuity of each individual conductor. The wire map indicates continuity to the remote end, shorts between two or more conductors, reversed pairs, split pairs, transposed pairs, and any other miswiring.

wire map tester - An instrument used to determine circuit opens, shorts, crossed pairs, improper wiring, and the determination of proper pin configuration; additionally, some units indicate cable length.

wire mesh grip - A device attached to the end of a cable, which facilitates the pulling of cable. Also called a mesh grip.

wirewrap - Termination of conductors by wrapping the conductor around a post.

witness lines - In telecommunications cabling, the visible physical impression made by cabling that is installed adjacent to the surface.

work area (work station) - A building space where the occupants interact with telecommunications terminal equipment.

work area cable (cord) - A cable connecting the telecommunications outlet/connector to the terminal equipment.

work area outlet - A connecting device for termination of horizontal media. See also telecommunications outlet/connector.

workflow - A groupware feature that guides multiple network users as they individually perform a sequence of tasks on a common document.

working group (WG) - A group of people temporarily working together to achieve some objective (e.g., development of a standard).

workstation - An information transport systems (ITS) device used in communicating with another ITS device.

worldwide interoperability for microwave access (WiMAX) - Popular name for the IEEE 802.16 wireless standard for metropolitan area networks. Data rates to 70 Mbls and ranges to 48 km (30 mi).

wye - A power system in which only one point (usually the midpoint of a supply transformer bank) is grounded. If the neutral is present, it is not grounded along the line.

X.25 - An established communications service for digital transmission over extended distances. Developed in the 1960s, it is the first large-scale implementation of packet switching technologies. Sometimes described as a packet switched data network. xDSL - A family of digital technologies designed to provide' high data transfer rates over existing (legacy) telecommunications circuits. See also digital subscriber line.

Yagi array antenna - A tree-shaped antenna named for its designer, Hidetsugu Yagi. The Yagi antenna uses one of more director elements to focus the radiated signal in one direction or plane.

zero-dispersion wavelength - Wavelength at which the chromatic dispersion of an optical fiber is zero. Occurs when waveguide dispersion cancels out material dispersion.

Z-gap - Spacing in fusion splicing.

zip-cord - In optical communications, a twofiber cable consisting essentially of two single-fiber cables having their jackets conjoined by a strip of jacket material.

zone - A specific area of protection, or a portion of a large protected area. In wireless networking, a zone consists of one access point (AP) and the group of devices associated with that AP. Also called a cell.

zone box - An enclosure used to house one or more of the following: a consolidation point, a horizontal connection point, building automation system outlets.

zone cabling - See open office cabling.

zone of protection - The area in close proximity to and within a building's lightning protection system. Several factors may make this area relatively immune to direct lightning strikes.