M m See micro. M See mega. M16QAM Modulation Motorola's modulation technology, M16QAM allows each divided information pathway to transmit at a 64K bit per second rate. MAC 1. Multi-Access Computing. 2. Message Authentication Code. 3. Mandatory Access Control. 4. Media-Access Control. MAC (Media Access Control) sublayer One of the two components that the IEEE 802 standard defines in the data link layer of OSI. The MAC sublayer is concerned with the traditional layer 2 functions like framing and error detection. machine language A binary language (using 0s and 1s) used directly by a machine. machine-oriented code A code whose words and syntax are designed for use on a specific class of computers. macro A group of frequently used commands or routines that are combined into a single command (macrocommand) that, on a computer, are accessible with one or two keystrokes. MACROL Macrolanguage (programming language for macro instructions). MAD Michigan Algorithmic Decoder. magenta 1. One of the colored inks used in four-color printing. 2. A color image compression technique developed at Los Alamos National Laboratory and patented by Paradigm Concepts. magnetic bubble storage Storage medium composed of a very thin layer of magnetic garnet material; under the influence of external fields, the bubbles can be maneuvered to represent information bits. magnetic core A device that can assume and maintain either of two magnetized conditions to provide storage, gating, or switching. magnetic disk A circular, flat plate with a surface layer that is magnetizable to store magnetic recordings on one or both sides. magnetic ink Ink that can be read by a magnetic scanner; used to print account numbers on bank checks. magnetic storage Any device that utilizes the magnetic properties of materials to store information. magnetic tape A tape impregnated or coated with magnetic material upon which data can be stored by magnetic recording. magneto-optical A high-density, erasable recording method. magnetography A Honeywell Bull printing method that uses a drum-like disk to transfer an image to paper. mailslot The open slot in front of a jukebox, used for inserting disc cartridges into the jukebox. main distribution frame (MDF) Wiring arrangement, sometimes carrying protective devices or functioning as a central testing point, that links that telephone lines from outside with internal lines. main PBX The PBX directly connected to a tandem switch via an access trunk group. main satellite/service PBX feature permitting multi-location customers to consolidate multiple attendant positions (satellites) at one location (called the main). mainstream network management Network control and diagnostics performed by a host computer that depends on network functions integrated from end to end. MAL Memory Access Logic defined in IEEE 802.6. MAN See metropolitan area network. management information Necessary data or program results considered essential for decision making with regard to business operations and control. Management Information Base (MIB) Database of network management information utilized by the OSI Common Management Information Protocol (CMIP) and the TCP/IP Simple Network Management Protocol (SNMP) standard. manchester encoding A digital signaling technique in which there is a transition in the middle of each bit period. manual exchange Exchange where calls are connected through an operator. manual originating line service System where the attendant must complete all outgoing calls; all other calls are blocked. manual PBX PBX's where all calls (including intercom), must be routed through the attendant manual signaling Sends an audible signal to a predesignated phone when a button is pushed on a telephone. manual terminating line service Provides lines that necessitate that all calls be connected by the attendant. manufacturing automation protocol (MAP) Protocol developed by General Motors in 1982 as a means of optimizing the operation of machines and other automated systems in factories. MAP 1. Memory Allocation Processor. 2. Memory Allocation and Protection. 3. Manufacturing Automation Protocol. map 1. A set of data that has a corresponding relationship to another set of data. 2. A list of data or objects as they are currently stored in memory or disk. 3. To transfer a set of objects from one place to another. 4. To relate one set of objects with another. MAP/TOP Manufacturing Automation Protocol/Technical Office Protocol; a cooperative industry effort to use the OSI model for computer communications and to adapt it for use in manufacturing and technical office environments. MAPICS Manufacturing and Production Information Control System (IBM). mapping 1. The establishment of one-to-one correspondence between two sets of data. 2. The translation of one group of data into a new set of data. MARECS European maritime satellite. MARISAT Maritime satellite service. mark 1. On microfilm, the same as a blip - a small character printed or notched on microfilm for timing or counting purposes. 2. On an optical disc, the pit, hole, bubble, light-reflective area or magnetic domain that signifies a written bit of information. mark geometry The size and shape of the mark made by a laser on an optical medium. maser (Microwave Amplification by Stimulated Emiss The general class of microwave amplifiers based on molecular interaction with electromagnetic radiation. The nonelectronic nature of the maser principle results in very low noise. masking 1. A method of transforming one set of data into another while blocking or excluding some data from this process on the basis of code patterns or position. 2. Protecting part of an image from change while manipulating the area around or behind it. MASM Macroassembler. massively parallel processing Parallel processing architecture that uses hundreds or thousands of processors. master control program Program that directs the operation of a system and its memory. master file Relatively permanent file that is an authority in a specific job, though its contents may change. master number hunting Routing pattern in which a call addressed to a pilot number of a hunt group will connect to the first non-busy station in the group. If a call is addressed to a specific station in the hunt group, it will go straight to the station and not hunt to another station in the group. master station Unit, in a telephone system or LAN, that controls all other stations in the system. In a LAN, this is generally accomplished through polling. master terminal A terminal that can communicate with all other terminals in a network. Only one terminal can be master at any one time. mastergroup (MG) 240 circuits processed as a unit in a carrier system. matrix 1. A switch used for moving calls from one input to the requested output. 2. An arrangement of elements (dots, LEDs, CCD elements, etc.) in a column-by-row, x-axis by y-axis layout. matrix printer Printer that represents characters in a specific pattern of dots. Also called dot matrix printer. MAU See multistation access unit. Mb Megabit (million bits). MB Megabyte (million bytes). Mbps Megabits per second; 1,000,000 bps. MBU Memory Buffer Unit. MCA Micro Channel Architecture (IBM). MCAD Mechanical Computer-Aided Design. MCR 1. Magnetic Ink Character Reader. 2. Magnetic Ink Character Recognition. MCU See multipoint control unit. MD-IS Mobile data intermediate. MDES Multi-Data Entry System. MDF See main distribution frame. MDNS A European public value-added network (VAN) operator. MDP Maintenance Diagnostic Processor. MDS 1. Microprocessor Development System (Motorola). 2. Modular Disk Storage. mean time between failure (MTBF) The average length of time during which a system or component operates without fault. mean time to repair The average time elaspe between the discovery of a fault in a system or component and its correction. measure The width of a line expressed in points. measured rate service Telephone service where charges correspond with line utilization. mechanical Camera-ready hard copy that is to be shot and converted to a negative for printing purposes. media 1. In transmission, the paths along which signals pass, i.e., optical fiber, cable, waveguide, radio wave, etc. 2. Instruments that carry data or information such as magnetic disks and cartridges. media access control sublayer See MAC sublayer. media file A file containing multimedia data, such as sound or animation. medium 1. Material on which data may be represented. 2. Material substance used for transmitting telecommunications signals (i.e., optical fiber, cables, water, radio waves). medium frequency Frequencies between 300 and 3000 KHz. medium scale integration Integrated logic circuits containing functions in between small-scale and large-scale integration; usually 10 to 100 gates are produced on a silicon chip. meet-me conferencing A feature allowing a conference of all parties dialing the same number. meet-me paging A facility to access voice paging equipment and subsequent automatic connection after the answered party acknowledges the page; the calling station goes off hook after paging. mega (M) A prefix for one million (10) times a specific unit. megabit One million bits. megabyte One million bytes. megahertz (MHz) One million hertz. memory 1. The computer's workspace -- physically a collection of RAM chips. 2. Any means of recording data, either permanently or temporarily, for later retrieval. memory address Storage locations that are distinguished by their addresses. memory dump Listing of the contents of a storage device, or a part of it. memory location Particular site within a computer storage device. memory management Manages the function of user programs in a multiprogramming medium. memory map A representation of what type of data is stored, and where, in a computer's memory. memory protection See storage protection. menu A list of displayed options from which an operator can select the next function. MERS Most economical route selecting. See least cost routing. MESA Modularly Expandable System Architecture (Centigram). message An ordered series of characters, words, or symbols intended to convey information, and whose contents, which generally contain a heading, text, and an end-of-message symbol, are delivered as an entity. message accounting See station message detail recording. message address The information contained in the message header that indicates the destination of the message. message control packet The control information in the storage area allocated to each message that remains uniquely associated with the message for the duration of its stay in the system. message feedback A technique of checking the accuracy of transmission of data in which the received data is returned to the sender for comparison with the original data. message format The rules for establishing parts of a message such as its header, address, text, and ending. message registration A phone system feature, usually employed in hotels, that details the number of message units contracted by each phone. message relay PBX feature permitting a caller to record a message and then have it transmitted to another phone at a designated time. message switching The technique of receiving a message, storing it until the proper outgoing line is available, then retransmitting it, with no direct connection between incoming and outgoing lines. Also called line-switching and store-and- forward. message unit (MSU) A unit of measurement used in charging for local messages, based on time and distance. message unit call A call made within the calling station's local service area and charged against the message unit allowance during a fixed billing period. message unit detail study (MUD) A report compiled by the local telephone company that details a user's outgoing calls over a given period. message waiting A service, usually found in hotels and large corporations, where a lamp or other device on a phone alerts a user (guest) that a phone message has been received and is being held either by a computer, message center, operator, or receptionist. metacode The formatting code used by Xerox centralized printers. metal oxide semiconductor (MOS) A type of computer memory utilizing 1/4-inch-square slices of silicon. These silicon slices require constant electric current for the data to be retained. metropolitan area network (MAN) A communications network that spans geographical areas whose size is between that of a local area network (LAN) and a wide area or long-distance network (WAN). metropolitan fiber ring An advanced, high-speed local network that can also be used to connect businesses and residences directly to a long distance carrier's network, and provide alternatives to the local telecommunications services that they have. metropolitan statistical area (MSA) The top 306 urban areas licensed by the Federal Communications Commission to provide cellular service. MF See medium frequency, multifrequency. See also dual-tone multifrequency signaling (DTMF). MFLOPS Million floating-point operations per second. MG See master group. MHS Message Handling System; allows messages of any content to be put into standard envelopes for delivery to a specified destination via electronic mail. MHz See megahertz. MIB See management information base. MIB-I Management information Base-I, the initial collection of objects and attributes defined by the TCP/IP standards. MICR Magnetic Ink Character Recognition. micro (M) A prefix for one millionth (10) of a specific unit. Micro Channel Architecture IBM's peripheral-expansion architecture developed for the PS/2 computer. micro-host See micro-mainframe link. micro-host link See micro-mainframe link. micro-mainframe link A hardware and/or software product that supports communications between a PC and a host computer (i.e., typically a mini- or mainframe). The most common type of link enables the PC to emulate a terminal supported by the host computer. microcell Antennas with limited coverage ranges, located in interior spaces and linked to a standard cell site. Microcom Networking Protocol (MNP) A proprietary error-connecting protocol for modems developed by Microcom. microdiskette A 3.5-inch magnetic storage medium that can typically store 720K bytes of data. Also called micro floppy. microfiche A 4 x 6 sheet of film containing several thousand miniaturized document pages. microfilm A continuous film strip that holds several thousand miniaturized document pages. microprocessor Main logic and control component of a microcomputer system whose principal elements and execution instructions are generally contained on a single integrated chip. microprogramming Combining basic, elemental computer operations to create higher level functions on the computer. microsecond (msec) One millionth of a second. microwave 1. An electromagnetic wave between one centimeter and 100 centimeters (10 Hz) in length. 2. Those frequencies in the super- high-frequency (SHF) band used for data and voice communications. 3. Electromagnetic waves in the radio-frequency range of 890MHz to approximately 30GHz; used for line-of-sight transmission of voice, video, and data usually in the 2GHz, 4GHz, and 6GHz bands. microwave radio See microwave. midrange system A computer characterized by higher performance and a more comprehensive instruction set than that of a microcomputer. MIFF Multimedia Interchange File Format; a file format standard, defined and developed under Apple Computer, for handling compound documents that may contain any mixture of graphics, text, and sound. migration Moving data and images from on- and near-line storage to off-line storage and vice versa. MIL Micro Implementation Language (Unisys) equipment, munitions, and software. Used in applications such as avionics and weapons guidance. Mil One one-thousandth (1/1000) of an inch; used to describe paper and tape thickness. milli (m) A prefix for one thousandth of a specific unit. millisecond (msec) One thousandth of a second. MIME Multipurpose Internet Mail Extensions. MIOP 1. Master Input/Output Processor. 2. Multiplexer Input/Output Processor. MIP Machine Instruction Processor. mips Million Instructions Per Second. mirrored server A server that entails the use of two hard disks of similar size, and a single disk channel over which the disks can be mirrored. All data written to the primary disk is automatically copied onto the other disk, with the second disk becoming operational if the primary disk fails. mirroring A fault tolerance method in which a backup data storage device maintains data identical to that on the primary device and can replace the primary if it fails. MIRS Motorola Integrated Radio Systems is a high capacity digital radio technology. MIS Management Information Systems. miscellaneous trunk access A feature that facilitates access to external and customer-provided facilities and equipment (e.g., FX, WATS, CCSA, tie, exchange network, paging, and code calling). MISD Multiple Instruction Stream/Multiple Data Stream. misread A character that is translated incorrectly. mixed station dialing The ability to simultaneously use rotary and push-button sets with all features provided to either type of telephone. mixer An electronic device for combining the signals from various sources onto one track. MJPEG (Motion JPEG) A method of video compression where each frame or field is compressed using JPEG. MLI Message Level Interface. MLPPP See multilink point-to-point protocol. MMDS Multichannel Multipoint Distribution Service, two sets of four channels each, also called "Wireless Cable". MMS Manufacturing Messaging Specification. mnemonic Generally refers to a term, usually an acronym or an abbreviation, that assists the human memory in remembering something (e.g., SCUBA is Self-contained, Underwater Breathing Apparatus). MNP See microcom networking protocol. MNP Level 10 Microcom networking protocol providing error- correction and compression for "dirty" telephone lines. See also microcom networking protocol. MNP Level 9 Microcom networking protocol providing "turbo" mode error-correction and data compression. See also microcom networking protocol. MNP Levels 2, 3, and 4 Microcom networking protocol providing three progressive levels of error-correcting performance. See also microcom networking protocol. MNP Levels 5 and 7 Microcom networking protocol providing two progressive classes of data compression compatible with MNP Level 4 error correction. MNP Level 5 offers 2-to-1 data compression for 1200 bps and higher modems. MNP Level 7 offers 3-to-1 data compression. See also Microcom Networking Protocol. MNP Levels 6 and 8 Microcom networking protocol providing error correction and compression protocols for half-duplex modems. See also microcom networking protocol. MO See Magneto-optical. mobile earth station A portable terminal capable of transmitting, receiving, and processing data communicated by satellite. mobile telephone exchange (MTE) Switching center that manages calls in a cellular phone system. mobile telephone service (MTS) Radio-telephone service which provides vehicles with two-way access to public telephones and other mobile telephone stations. See cellular telephone. mobile telephone switching office (MTSO) The switch that routes and connects calls between cellular and landline systems. MODCA Mixed Object Document Content Architecture. mode 1. Method of operation. 2. In a statistical sense, the most recent value. mode of operation In a given situation, the method of processing data. modeling See simulation. modem (modulator/demodulator) A device that provides compatibility between digital data processing devices and analog transmission facilities by converting serial digital data from a transmitting terminal to an analog signal suitable for transmission over a telephone channel; a similar device then reconverts the signal to serial digital data for the receiving terminal. modem pooling Allows a terminal in a PBX system to access outside terminals through various modem groups that operate at different speeds. modem sharing unit (MSU) Device enabling more than one terminal to share a modem. modular Referring to a unit which is made up of various subunits that can be combined in a variety of ways. modulation The process by which some characteristic of a single wave is varied in accordance with another wave or signal. modulator Device that converts a voice or data signal into a transmittable configuration. module 1. Discrete and identifiable program units, hardware, or software. 2. In bar code, it's the smallest-width element, either bar or space. moire The undesired effect caused by overlaying dot patterns (usually halftones of photographs) which are incompatible. An independent pattern emerges when the two geometrically regular patterns intersect. moisture content The amount of water held in paper affects the production of a high-speed laser printer or copier. A high moisture content causes jams. MOL Machine-Oriented Language. monitor 1. A video display. 2. Any hardware or software that supervises the operation of a system and indicates any deviation from its standard operating procedure. monitoring Permits certain stations to listen in on other stations in the system. monospacing Uniform horizontal spacing. MOON Magneto Optical On Network. MooV An Apple-proposed standard format for storing the basic elements of multimedia (video, animation, sound and text) that is incorporated into QuickTime. MOP 1. Multiple On-line Processing. 2. Multiple On-line Programming. morphing The process of automatically transforming one shape into another over a specified range of frames. morse code Dot-dash code used in early line-telegraphy that is still in use in radio telegraphy to ships at sea where machine codes and MARISAT satellite antennas have not yet been installed. MOS See metal oxide semiconductor. Mosaic A video effect that blurs a video image by copying every nth pixel n-1 times into adjacent pixels. moth-eye An optical disk medium in which the disk surface is textured so that the laser marks stand out more dramatically from the surface, enabling the placement of marks closer together and the packing of more data into less space. motherboard Main integrated circuit board of a computer system. mouse A small peripheral, a little larger than a deck of cards, used in place of a keyboard to control cursor movement and to perform editing, graphics, and menu- selection functions. MPA Multipoint asynchronous. MPE 1. Memory Parity Error. 2. Multiprogramming Executive (Hewlett-Packard). MPEG Video compression standard. MPL Message-Processing Language (Unisys). MPP Memory Parity and Protect. MPR II The Swedish government standard for maxiumum video terminal radiation. MRJE Multiple Remote Job Entry. MRP Material Requirements Planning. MRP II Manufacturing Resource Planning. MS-DOS Microsoft Disk Operating System (Microsoft). MS-NET Microsoft software product that provides the basis for IBM's PC Network. MS-NET defines resource servers and redirectors. MSA Metropolitan Statistical Area. When the Federal Communications Commission issued cellular radio licenses it divided the United States into MSA and Rural Service Area (RSA) markets. MSBF Means Swaps Between Failure. A better way to judge the reliability of a jukebox or changer. Measure of the number of disk exchanges a jukebox completes before experiencing mechanical failure. msec See millisecond. MSF Mass Storage Facility. MSI Medium-Scale Integration. MSP Mass Storage Processor. MSU 1. Mass Storage Unit. 2. Modem Sharing Unit. 3. See message unit. MTA 1. Message Transfer Agent; functions as a local post office for exchanging messages with local user agents (UAs), as well as relaying the messages of local and remote UAs to other MTAs. 2. Major Trading Areas. MTBF See mean time between failures. MTE See mobile telephone exchange. MTM Multiple Terminal Manager (IBM). MTS See mobile telephone service. MTTF Mean Time To First Failure; a measurement of equipment reliability that states the average (mean) time after installation that the equipment can sustain use until it initially fails. MTTR See mean time to repair. MTU Magnetic Tape Unit. MTX See mobile telephone exchange. MU See message unit. mu-law Method of encoding audio signals used in U.S. standard 24 channel PCM systems. MUD See message unit detail study. multiaccess The ability of users, working independently, to simultaneously communicate with a computer. MULTIBUS Intel system bus. multicast An LMI option that allows a frame relay device to broadcast frames to multiple destinations. MULTICS Multiplexed Information and Computing Service (Bull HN operating system). multidrop A term applied to systems in which several points are served by the same circuit. multidrop line Communications channel that interconnects several stations in different geographical locations. Also called multipoint link. multifrequency A signal made of two or more frequencies. multifrequency The ability of a monitor to accept and synchronize to many different frequency inputs, making the single monitor more flexible and of higher value. multifunction drive An optical drive which can use both WORM and rewritable media. multileaving Typically a bisynchronous transmission of a varying number of data streams between user devices and a computer. multilink point-to-point protocol (MLPPP) The standard method for inverse multiplexing data over separate physical links. multimedia Combining multisensory media (reading, seeing video, hearing music, and speech), delivered electronically, usually to the desktop, for the dissemination of information. multimode fiber A thick cored (50-200 microns), glass fiber for carrying lightwave communications. multiple access The connection of a subscriber or user to two or more switching centers by separate access lines using a single message routing indicator or telephone number. multiple classes of service Features and restrictions grouped and assigned according to the type most closely meeting the user's calling pattern and needs. multiple customer group operation A PBX shared by several companies, with separate trunks and consoles for each. multiple listed directory number service Allows for more than one directory number to be listed for a PBX. multiple trunk groups Indicates that the switching system is capable of being equipped for more than one group of trunk circuits. multiplex Transmission of more than one signal over a communications channel. multiplexer A hardware device that permits transmission of multiple signals over a communications channel, enabling several communications lines to be attached at the same time for simultaneous transmission and reception of messages. multiplexing Several information streams are combined for transmission over one medium using frequency-division or time- division techniques. multipoint A circuit providing simultaneous transmission among three or more separate points. multipoint control unit (MCU) A device that allows video codecs at multiple sites to be linked into a single session. multipoint line A communications channel to which more than one terminal is attached; only one may transmit at any given time, though several may receive. multiprocessing Simultaneous processing with two or more processors in one computer or two or more computers processing together. multiprocessor System possessing two or more communicating processing units. multiprogramming A technique for handling multiple routines or programs seemingly simultaneously by overlapping or interleaving their execution. multistation access unit (MAU) Wiring concentration used in the IBM Token Ring Network and other LANs. Up to eight token-ring PCs are connected to one MAU, with MAUs cabled to one another to form a token ring. multistrip scan The results of a hand scan. Hand scanner software can stitch multistrip scans together to recreate the original image. Multisync monitor A monitor that adjusts to the type of video signal it receives. MultiSync is trademarked to NEC. multitasking Performing serveral tasks simultaneously on one computer. multitenant sharing The ability for multiple user groups to share a telephone system. multithreading Simultaneous processing of more than one message by an application program. multiuser A computer that has several workstations attached to it so that multiple users can simultaneously access it. mux See multiplexer. MVP Multiple Virtual Processing. MVS Multiple Virtual Storage; IBM's production operating system for large computer environments and successor to the OS/360. MVS/ESA Multiple Virtual Storage/Enterprise Systems Architecture (IBM). MVS/SE Multiple Virtual Storage/System Extension (IBM). MVS/SP Multiple Virtual Storage/System Product (IBM). MVS/XA Multiple Virtual Storage/Extended Architecture (IBM). MVT Multiprogramming Variable-Task (IBM). MVT/TSO Multiprogramming Variable-Task/Time-Sharing Option (IBM).