V v Volts. V Vector. V.21 ITU-TSS standard for 0-300 bps full duplex dial-up modems. V.22 Standard for 1200-bps, full-duplex, dial-up or leased line modems. V.22bis Standard for 2400-bps, full-duplex, dial-up modems. V.23 ITU-TSS standard for 600- and 1200-bps, dial-up modems. V.24 ITU-TSS list of definitions for interchange circuits between DTEs and DCEs. V.25 ITU-TSS standard for dial-up automatic calling or answering equipment. V.26 ITU-TSS standard for 2400-bps, leased-line modems. V.26bis ITU-TSS standard for 1200- and 2400-bps dial-up modems. V.26ter ITU-TSS standard for 2400-bps, full-duplex, dial-up modems. V.27 ITU-TSS standard for 4800-bps, leased-line modems. V.27bis ITU-TSS standard for 2400- and 4800-bps, leased-line modems. V.27ter ITU-TSS standard for 2400- and 4800-bps, dial-up modems. V.28 ITU-TSS standard for electrical characteristics of interchange circuits. V.29 ITU-TSS standard for 9600-bps, point-to-point, four-wire, leased-line modems. V.32 Standard for 9600-bps, two-wire, duplex, leased- and dial-up line modems. V.32bis Standard for 14.4K-, 12K-, 9600-, 7200-, 4800-bps, dial-up line modems. V.33 Standard for 14.4K-bps, point-to-point, four-wire, leased-line modem connection. V.35 Standard for data transmission at 48K-bps using 60- 180KHz wideband circuits. V.42 Standard for error-correction that uses LAP-M as the primary protocol and provides MNP Classes 2 through 4 as an alternative protocol for compatibility. V.42bis Standard for real-time, 4-to-1 data compression that is based on British Telecom's Lempel Zev (BLT2) algorithm. V.54 Standard for modem loopbacks. V.Fast A name for modems capable of data speeds up to 28.800 bits per second. VA Volt ampere. VAB See voice answerback. VAC Volts alternating current. vacant code intercept Routes all calls erroneously dialed using an unassigned first digit to the attendant, a busy signal, a "reorder" signal, or to a recording. vacant number intercept Routes calls of unassigned numbers to the attendant, a busy signal or a recording. VAD Value Added Dealer. VADS Value added data network. See Value added network. validity check Test to ensure the quality of transmission. value The relative lightness or darkness of a color. value-added carriers Vendors that supply special features to services purchased from other carriers and resell the service. value-added network (VAN) A communications network that provides additional features (e.g., message switching and protocol handling) that extend beyond those offered in traditional networking environments. See also specialized common carrier and other common carrier. value-added service Communications company that utilizes the common carrier networks for transmission but supplies enhanced data features via specialized equipment. VAN See value-added network. VANS Value-added network Service. See value-added network. VAP Value Added Program. VAPC See vector adaptive predictive coding." VAR Value Added Reseller VAR Value Added Reseller. An organization that adds value to a system and resells it. variable Quantity that can assume any given set of values. variable-length record Record whose length depends on other related records. VAX Virtual Architecture Extended (Digital Equipment computer series). VAXBI VAX Bus Interconnect (Digital Equipment). VDC Volts direct current. VDI Virtual Device Interface. VDT 1. Video display terminal. 2. Visual display terminal. See cathode ray tube. VDU Visual display unit. Preferred term in Europe. vector Images defined by sets of straight lines, defined by the location of the end points. vector adaptive predictive coding (VAPC) An audio coding algorithm primarily for use at the lowest transmission aggregate bit rates. vector display Terminal that displays images with vectored line segments, rather than pixels. vector sum excitation linear predictor A technique that digitally codes and compresses voice signals. vectorization Translation of a pixel-based image to a vector-based image. velox A halftone print. Used to paste-up mechanicals with halftones in place, saving negative stripping work, and costs. Veronica A search tool for files stored on Gopher servers. vertical recording A magnetic disk recording technique that increases the available storage space. vertical redundancy check (VRC) In ASCII-coded blocks, the parity test (even or odd) performed on each character in the block. See also parity check. vertical scan frequency Same as refresh rate, expressed in hertz. very high frequency (VHF) Frequencies between 30MHz and 300MHz; television channels between 2 and 13. very large scale integration (VLSI) Over 10,000 transistors per chip. See also large scale integration. very low frequency (VLF) Frequency range from 3KHz to 300KHz. very small aperture terminal (VSAT) Terminal for individual corporate satellite communications which consists of one master earth station (MAS) and numerous two-way satellite terminals. VF See voice frequency. VGA Video Graphics Array. Standard IBM video display standard. VGDF See voicegrade data facility. VGF See voicegrade facility. VHD Very High Density. Techniques of recording 20 megabytes and more on a 3 1/2" magnetic disk. VHF See very high frequency. video 1. The portion of the frequency spectrum used for TV signals. 2. A signal with a bandwidth of approximately 5MHz generated from TV scanning. video capture Converting a video signal into a format that can be saved onto a hard disk or optical storage device and manipulated with graphics software. video compression The process of reducing a digital video signal. video dial tone Provides video to offices and houses without affecting the content of the video signal. video digitizer Same as frame grabber; a device that changes a video picture into a digital computer graphics language. video disk A record-like device that is capable of storing large amounts of audio and visual data. video signal Electromagnetic frequency needed to transmit moving pictures, requiring one to six MegaHertz. videoconferencing Teleconferencing where participants are able to see as well as hear one another. videodisc Read-only, 12-inch direct access optical disc standard for storing and playing video. videotex An information service that uses a slightly modified domestic television receiver in conjunction with a normal public telephone line in order to provide an interactive computerized data retrieval service for homes and offices. viewdata See videotex. VINES VIrtual NEtworking Software; the core of Banyan's LAN. VIP 1. Vector Image Processor. 2. Virtual Input/Output. 3. Video information provider. virtual address Address that identifies the byte location in virtual storage. virtual circuit A connection between two points in a data network that uses different circuits during a transmission but behaves as a dedicated path. virtual filestore An abstract model describing a filestore (e.g.,data base or similar construct) and how users interact with it. virtual memory or virtual storage A technique that simulates the availability of additional workstation memory in order to let users run multiple programs concurrently. virtual storage Storage space that may be viewed as addressable main storage to a computer user, but is actually auxiliary storage (usually peripheral mass storage) mapped into real addresses. See virtual memory. virtual storage address Memory location. virtual telecommunications access method (VTAM) Mainframe software interface to data communications devices. VTAM is used by IBM's system network architecture (SNA). Virus A destructive computer program that replicates itself throughout a network. Viruses can delete files, create erroneous data, slow system operation, and prevent applications from saving files. See also worm. visually impaired attendant service Service that extends the normal visual signals on an attendant console with special tactile devices and/or audible signals to enable a visually impaired person to function as an attendant. VLF See very low frequency. VLSI Very large scale integration. See large scale integration. VM 1. Virtual Machine (IBM). 2. Virtual Memory. VM/BSE Virtual Machine/Basic System Extensions (IBM). VM/CMS Virtual Machine/Conversational Monitor System (IBM). VM/SE Virtual Machine/System Extensions (IBM). VM/SP Virtual Machine/System Product (IBM). VMA Virtual Machine Assist (IBM). VME Virtual Machine Environment. VMS Virtual Machine System operating system (Digital Equipment). VMTP Virtual Machine Terminal Protocol. VNM Vitual network machine. vocoder A voice processing technique that converts spoken language into digital information. The digital code is transmitted and encoded at the receiver. VOD Video-on-demand. voice activated dialing Allows the user to dial a number by calling the number out to the cellular telephone. voice answerback (VAB) Provides voice responses to inquiries made from telephone-type terminals. The audio response is composed of a limited digitized voice vocabulary prerecorded on a magnetic drum or disk file and produced by an audio response unit and a computer. voice band See voicegrade channel. voice digitization Conversion of analog voice signals into binary or digital signals for purposes of transmission or storage. voice frequency (VF) Any of the frequencies in the band 3000 to 3400Hz that must be transmitted to reproduce the voice with reasonable fidelity. voice mail Device that stores, records, and retrieves voice messages. A standalone device refers to a basic phone answering machine connected to a telephone set. An integrated system is used on a much larger scale in, for example, a business or corporation. voice mail module interface A feature that facilitates voice message recordings for later retrieval. voice message service (VMS) Leased service providing a phone user with the ability to access a voice mail system and leave a message for a particular person. voice paging See paging. voice paging access Permits attendants and phone users entry to loudspeaker paging equipment. voice print Used like a fingerprint, a voice print identifies an individual by his or her unique voice pattern. voice recognition Computer's ability to recognize a human voice and act on commands given. voice response unit (VRU) A device able to produce a spoken message from a selection of stored words. voice store-and-forward (VSF) system PBX feature which permits the storage and remote retrieval of messages. voice synthesis Computer-generated voice. voicegrade An access line suitable for voice, low-speed data, facsimile, or telegraph service. It, generally, has a frequency of about 300 to 3400Hz. voicegrade channel A channel with bandwidth equivalent to a telephone channel obtained through the public telephone network. voicegrade data facility (VGDF) A facility with an approximate bandwidth of 300Hz to 3400Hz suitable for data transmission, remote metering, supervisory control, and miscellaneous signaling purposes. voicegrade device A communications channel that is usually 4000Hz, and can pass voice sounds in the band 300Hz to 3000Hz. voicegrade facility (VGF) A circuit designed to DDD network standards which is suitable for voice, low-speed data, facsimile, or telegraph service. volatile storage A type of data storage facility that retains information when power is lost. volume control The ringing, monitor, and handset volumes can be adjusted. VOTS VAX OSI Transport Services (Digital Equipment). VP 1. Vector Processor. 2. Virtual Processor. VRAM Virtual Random Access Memory. VRC See vertical redundancy check. VS 1. Computer series (Wang). 2. Virtual Storage. 3. Virtual System (Unisys). VSA Virtual Storage Access Method. VSAM Virtual Sequential Access Method (IBM). VSE Virtual Storage Extended (IBM). VSE/AF Virtual Storage Exhibit/Advanced Function (IBM). VSELP See Vector sum excitation linear predictor. VSF See voice store and forward. VSM Virtual Storage Management. VT -- Virtual Terminal Defined in ISO 9041. VTAM See virtual telecommunications access method. VTOC Volume Table Of Contents. VTP Virtual Terminal Protocol. VTR Video Tape Recorder.