E E 1. Execution. 2. See Erlang. E&M signaling A form of signaling using separate leads (the E&M leads) for supervisory signaling and for transmitting voice or data. The E lead receives ground or is open from the signaling unit, and the M lead transmits battery or ground to the signaling unit. E-bone European backbone. E-Mail See electronic mail. E1 Europe's digital transmission link with a capacity of 2.048M bps. E3 Europe's digital transmission link with a capacity of 34.368M bps (Japan's 3rd level 32.064M bps). EAROM See electrically alterable read-only memory. earth stations Ground terminals that use antennas and associated electronic equipment to transmit, receive, and process satellite communications. Also called ground station. EAS See extended area service. EAX See electronic automatic exchange. EBCDIC (extended binary coded decimal interchange A code that uses eight binary positions to represent a single character and provides for 256 bit pattern. ECC 1. Error checking and correction (memory protection) 2. error-correcting code; an error-detecting code that incorporates additional signaling elements and enables errors to be detected and corrected at the receiving end. 3. European Community Commission. 4.See established common carrier. echo Part of a signal transmission reflected or otherwise returned with sufficient magnitude and delay to be received as interference. echo cancellation In high speed modems, the technique that filters out and isolates unwanted signal energy caused by echoes from the main transmitted signal. echo canceller A device that eliminates or reduces echo. echo check A method of checking data transmission accuracy in which received data is returned to the sending end for comparison with the original data. echo return loss (ERL) The attenuation of echo currents in one direction caused by telephone circuits in the other direction. echo suppressor A line device used to prevent energy from being reflected back (echoed) to the transmitter. It attenuates the transmission path in one direction while signals are being passed in the other direction. echoplex A communications procedure where characters keyboarded by the operator and sent to a computer using full-duplex transmission are echoed back, ensuring that data was correctly received. ECL 1. Executive Control Language. 2. Emitter-Coupled Logic. ECMA European Computer Manufacturers Association; standards organization committed to the development of data processing standards. ECS European fixed-service satellite system. EDAC Error Detection And Correction (memory protection). EDC See error detecting code. EDDP Electronic Document and Printing Professional. A professional in the electronic document systems industry. EDI See electronic data interchange. EDIFACT Electronic Data Interchange for Administration Commerceand Transport; an OSI applications standard for the interchange ofcertain formatted transactional data content. edit 1. To make a change to existing data. EDL Edit Decision List. In video editing, a series of time-code numbers that describe a series of video clips, cuts, edits, and special effects. EDL controls the source deck(s), complies all the source material, lines up the clips and records everything to the recorder deck. EDMA Extended Direct Memory Access. EDMICS Engineering Data Management Information and Control System. The Navy's imaging initiative. EDMS Engineering Document Management System. EEHLLAPI Extended Edition High Level Language Application Programming Interface (IBM); an API that enables programmers to write applications on PCs that can communicate directly with mainframe computers. EEPROM Electrically erasable programmable read-only memory. Memory circuit in which an electric pulse erases all the stored memory to allow new data input. EEROM Electrically Erasable Read-Only Memory. EF Extended Facility (IBM). EFF Electronic Frontier Foundation, a membership organization that lobbies for basic freedoms on electronic networks. EFS External File Service. EFT Electronic Funds Transfer. EFTA European Free Trade Association -- which comprises Austria, Finland, Iceland, Liechtenstein, Norway, Sweden and Switzerland EGA Enhanced Graphics Adapter (IBM). EHLLAPI IBM's Extended High Level Language Application Program Interface. EIA See Electronic Industries Association. EIA interface Signal characteristics established by the EIA to standardize the transfer of information between data communications equipment and terminal equipment. The most famous interface is the RS-232-C connector. EIS Extended Instruction Set (Bull HN). EISA See Expanded Industry Standard Architecture. EKTS See electronic key telephone systems. electrically alterable read-only memory A memory unit whose contents are altered with electrical signals. electromagnetic interference (EMI) When electromagnetic energy causes an undesirable response in the operation of electronic systems or equipment. electromagnetic spectrum Range of frequencies or wave lengths present in electromagnetic radiation. electromechanical ringing Traditional bell or buzzer in a telephone that announces incoming calls. electronic automatic exchange (EAX) Non-AT&T term to refer to an electronic central office. AT&T's term is electronic Switching System (ESS). electronic data interchange (EDI) Software standards that enable different companies and different computers to exchange business documents over phone lines, computer-to-computer. electronic forms Graphics that are merged electronically with data to appear on each frame. Electronic Industries Association (EIA) An industry group that sets voluntary standards for electronic equipment. electronic key telephone systems (EKTS) Generic term indicating microprocessor-based key telephones that provide PBX-like features as well as access to multiple CO lines. electronic mail (E-mail) The transfer of messages, data, and applications over a network. electronic mail server A server containing software that allows network users to exchange messages via an "electronic mailbox", typically a user ID that permits access to a data base server where messages are stored for retrieval or filed for future reference. electronic publishing Producing and providing documents in electronic form. Not to be confused with publishing electronically (desktop publishing.) Electronic Superhighway A broadband network transporting voice, interactive, full motion data and video services. electronic switching system (ESS) A system using computer-like operations to switch telephone calls. electronic tandem network (ETN) 1. A private network automatically and electronically connecting the calling office to the called office through tandem-tie trunks. The network switches also function as PBXs. 2. An AT&T product name. 3. A generic term for a PBX-based network. electronic tandem networking The operation of two or more switching systems in parallel. electronic wastebasket An electronic mail feature that provides an area where unwanted messages can be sent for a predetermined amount of time before they are purged from the system. electrophotographic printing See electrostatic printing. electrostatic printing Printing process that uses a special paper which is charged by an electron beam. The tone sticks to the charged areas. Used in large-image plotters. elevator seek or sort A logical way of organizing many requests for data from a storage device, especially a jukebox, in order to speed up processing. ELLC Extended Logical Link Control protocol. embedded system A system which contains a computer system within. emergency line A PBX feature providing a specific line for making and receiving calls when the system is inoperative. emergency right of way See executive override. emergency transfer See power failure -- transfer. EMI See electromagnetic interference. EMIC Ethernet master interface card. EMS 1. Extended Memory Specification. 2. Elemental Management Systems. emulate The use of hardware and software on a PC to imitate the operation of a terminal at both the operator and communications interface sides of the connection, enabling the host computer supporting the emulated terminal to also support the PC. emulator A hardware device that provides a reliable model of the hardware environment for the new software, while interfacing with and controlling prototype hardware. The emulator is used to debug the software as well as prototype hardware and to integrate the two. This device is also know as an In-Circuit-Emulator (ICE) or integration unit. Encapsulated PostScript EPS, an image description format. See EPS. encapsulation In object-oriented programming, making both data and processing private (i.e., hidden) within an object. This allows the object to be modified without creating problems elsewhere in the program. encoding The basis of image compression. Strings of black or white pixels are replaced with (shorter) code numbers that describe them and their relationship to each other. encryption The process of encoding a message for security purposes for transmission over a public network. end node A nonrouting node (one that cannot forward packets intended for other nodes). An end node supports only a single active line. end of address The character used to separate the address or routing part of a message from the following parts of a message. Sometimes called end-of-routing symbol. end office A central office (CO) to which a telephone subscriber is linked. Also called Class 5 office. energy communications A feature enabling a PBX to communicate with energy consuming and monitoring devices in a hotel or other business. enhanced paging A paging service that supports fax and voice mail notification, extended text messages, and automatic voice dialing of cellular calling-party numbers. enhanced private switched communications service ( AT&T private line network that links very large businesses having multiple locations. enhanced SMR A circuit and packet-oriented digital wireless communications services that utilizes channels in the 800- to 900 MHz SMR bands. ENQ (Enquiry) Enquiry character; A control character used as a response request from the station to which a connection had been established. envelope delay Analog circuit characteristic that results when some frequencies arrive ahead of others, even though they were transmitted at the same time. EOM End-of-message (indicator). EOT 1. End of transmission. 2. End of tape. EP Emulation Program (IBM). EPA Enhanced Performance Architecture. EPABX Electronic private automatic branch exchange. See private branch exchange. EPROM See erasable programmable read-only memory. EPS Encapsulated Post Script Graphics Format; defined by AdobeSystems, PostScript is a page definition language (PDL) standard designed for use with certain laser printers and typesetting machines. EPSCS See enhanced private switched communication service. equal access The AT&T divesture settlement required that telephone users be provided with equal access to any designated long distance carrier. equalization The process of compensating for attenuation or line distortion. equalizer Any combination (usually adjustable) of coils, capacitors, and/or resistors inserted in a transmission line or amplifier circuit to improve its frequency response. erasable programmable read-only memory (EPROM) Nonvolatile memory initially programmed by the manufacturer, but which can be reprogrammed to conform with customer requirements. ERL See echo return loss. Erlang (E) A measurement of telephone traffic load (1 erlang = 1 circuit busy for 60 minutes, or 36 CCS). Erlang B A mathematical formula used to determine the traffic capacity of a given group of circuits. Erlang C Formula for designing telephone traffic management for PBXs and networks. It is used when traffic is random and there is queuing, and presupposes that callers will wait indefinitely to make their connection. ERP Error Recovery Procedure. error burst Transmitted signals containing more errors than the accepted predefined measure. error control An error management process. error detecting code (EDC) A code in which each telegraph or data signal conforms to specific rules of construction, so that departures from this construction in the received signals can automatically be detected. These codes require more signal elements than are necessary to convey the basic information. error rate A measure of data integrity, expressed as the fraction of flawed bits; often expressed as a negative power of 10 as in 10 (a rate of one error in every one million bits). error-correcting code (ECC) An error-detecting code that incorporates additional signaling elements and enables errors to be detected and corrected at the receiving end. ES-IS End system to intermediate system, an OSI protocol for access to a router-based network. ESA 1. Enterprise Systems Architecture (IBM). 2. European Space Agency. ESCON Enterprise System Connection, an IBM channel architecture. ESCORT Programming language (Unisys). ESDI (Enhanced Small Device Interface) Hard disk interface that transfers data in the one to three MByte/sec range. ESF See extended superframe. ESPOL Executive System Problem-Oriented Language (Unisys). ESPRIT European Strategic Program for Research and Development in Information Technologies. ESS See electronic switching system. established common carrier (ECC) A public utility authorized by a regulatory authority to transmit communications data for the public. ETACS Extended TACS. See TACS. Ethernet A baseband local area network (LAN) originally developed by Xerox and supported by Intel, Digital Equipment, and Hewlett-Packard. ETN See electronic tandem network. ETSI European Telecommunications Standards Institute. ETSS Entry Time-Sharing System (IBM). ETX End-of-text (indicator). EUTELSAT European Telecommunications Satellite Organization. even parity check (odd parity check) The transmitting device adds a parity bit (used for error checking) to a data word to make the sum of all the one bits either odd or even. exchange A defined area served by one or more central offices of a communications common carrier within which the carrier furnishes service at the exchange rate and under the regulations applicable in that area prescribed in the carrier's filed tariffs. Also the switching facility serving the exchange area. exchange area Geographic area in which phone services and prices are the same. exchange line socket 2- or 4-wire socket providing physical access to the PSTN. exchange, private automatic See private automatic exchange (PAX). exchange, private automatic branch See private automatic branch exchange (PABX). exchange, private digital See private digital exchange (PDX). exclusive hold A feature that enables a station user to place a call on hold; none of the other stations can retrieve the held call. See also Hold. executive override A PBX feature that allows authorized station users to join an existing conversation. Also called attendant busy override, busy override and intrude. Expanded Industry Standard Architecture (EISA) Personal computer bus standard that extends the capabilities of the IBM ISA bus. expandor A transducer that, for a given amplitude range or input voltage, produces a larger range of output voltages. One use is to expand the volume range of compressed signals. See compandor. expert system System that embodies the working knowledge of anexpert in a particular domain, such as finance and manufacturing. See also internal modem. extended area service (EAS) A service that allows subscribers, in return for an extra monthly premium, to originate calls within a fixed area outside their normal local area without toll charges. extended superframe (ESF) A channel bank framing format used for DS1 (T1) transmission. A superframe consists of 24 frames and uses a 6 bit framing pattern. extension, off-premise (OPX) An extension telephone or PBX station located on property not contiguous with that on which the main station or PBX is located. extension, PBX A term used to designate a telephone station connected to and/or served by a PBX. external modem Modem that attaches to a serial port and sits outside the computer, as opposed to an internal modem, which is a card (circuit board), inserted into a computer slot. eye-readable Images recorded on a microform which can be read without magnification. This is a relative term, as it depends on the quality of the eye in question.