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Reference / Glossary

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Cross References
m, M adj. The lower-case "m" is the internationally agreed abbreviation for the prefix "milli" (as in millimeter, meaning 1/1000th of one meter). The upper-case "M" is the international abbreviation for "Mega," meaning one million. "M" is also used to mean 1,048,576 (1K times 1K), as in "MB" or "MByte" or megabyte.
mail gateway n. A machine that connects two or more electronic mail systems (often, mail systems on different networks) and transfers messages between them.
mainframe n. A computer, usually in a computer center, with extensive capabilities and resources to which other computers may be connected so that they can share facilities. Originally referred to the central processing unit of a large computer, which occupied the largest or central frame (rack).
maintenance analysis procedure (MAP) n. A hardware maintenance document that gives an IBM service representative a step-by-step procedure for tracing a symptom to the cause of a failure.
mapping n. The process of converting data that is transmitted in one format by the sender into the data format that can be accepted by the receiver.
markup language n. A notation for identifying the components of a document to enable each component to be appropriately formatted, displayed, or used.
Maximize n. A choice that enlarges a window to its largest possible size.
Mb See megabit.
MB See megabyte.
M-bit n. More-data bit. In X.25 communications, the bit in a data packet that indicates that there is more data to follow in another data packet, when a message is too large for one packet.
Mbps n. Megabits per second.
mean time between failures (MTBF) n. For a stated period in the life of a functional unit, the mean value of the lengths of time between consecutive failures under stated conditions. .
mean time to recovery (MTTR) n. For a stated period in the life of a functional unit, the average time required for corrective maintenance.
media access port n. A hardware-addressable component (such as a communication adapter) of a node that gives the node access to a transmission medium and enables data to pass into and out of the node.
Meg n. Megabyte.
megabit (Mb) 1. n. For processor storage, real and virtual storage, and channel volume, 220 or 1 048 576 bits. 2. n. For disk storage capacity and communications volume, 1 000 000 bits.
megabyte (MB) 1. n. For processor storage, real and virtual storage, and channel volume, 220 or 1 048 576 bytes. 2. n. For disk storage capacity and communications volume, 1 000 000 bytes.
memory n. All of the addressable storage space in a processing unit and other internal storages that is used to execute instructions.
menu 1. n. A list of options displayed to the user by a data processing system, from which the user can select an action to be initiated. 2. n. In text processing, a list of choices displayed to the user by a text processor from which the user can select an action to be initiated. 3. n. A list of choices that can be applied to an object. A menu can contain choices that are not available for selection in certain contexts. Those choices are indicated by reduced contrast.
menu bar 1. n. The area near the top of a window, below the title bar and above the rest of the window, that contains choices that provide access to other menus. 2. n. In the AIX operating system, a rectangular area at the top of the client area of a window that contains the titles of the standard pull-down menus for that application.
merchant server n. In e-commerce, a Web server that offers cataloged shopping mesh network A network in which there are at least two nodes with two or more paths between them.
metadata n. Data that describes the characteristics of stored data; descriptive data.
metafile n. A file containing a series of attributes that set color, shape, and size, usually of a picture or a drawing. Using a program that can interpret these attributes, a user can view the assembled image.
metric n. In Internet communications, a value, associated with a route, which is used to discriminate between multiple exit or entry points to the same autonomous system. The route with the lowest metric is preferred.
microcode 1. n. One or more microinstructions. 2. n. A code, representing the instructions of an instruction set, that is implemented in a part of storage that is not program-addressable. 3. v. To design, write, and test one or more microinstructions.
middleware n. A vague term that refers to the software between an application program and the lower-level platform functions.
MIDI See Musical Instrument Digital Interface.
migrate v. To replace a particular software component or system with another software component or system.
migration n. The installation of a new version or release of a program to replace an earlier version or release.
MIME See Multipurpose Internet Mail Extensions.
MIP-burner n. A long-running program.
MIPS ("mipps") n. A measure of computer processing performance that is equal to one million instructions per second.
mixed-character string n. A string that can contain characters from both a single-byte character set and a double-byte character set.
mobile adj. Pertaining to computing that is performed on a portable computer or a handheld device by a user who is frequently moving among various locations and may be using different types of network connections (for example, dial-up, LAN, or wireless).
modem (modulator/demodulator) 1. n. A functional unit that modulates and demodulates signals. One of the functions of a modem is to enable digital data to be transmitted over analog transmission facilities. 2. n. A device that converts digital data from a computer to an analog signal that can be transmitted on a telecommunication line, and converts the analog signal received to data for the computer.
module n. A program unit that is discrete and identifiable with respect to compiling, combining with other units, and loading; for example, the input to or output from an assembler, compiler, linkage editor, or executive routine.
monitor 5. v. In the NetView Graphic Monitor Facility, to open a view that can receive status changes from Tivoli NetView for OS/390. Problem determination and correction can be performed directly from the view.
monitor [1] 1. n. A device that observes and records selected activities within a data processing system for analysis. Possible uses are to indicate significant departure from the norm, or to determine levels of utilization of particular functional units. 2. n. Software or hardware that observes, supervises, controls or verifies operations of a system.
monitor [2] 3. n. The function required to initiate the transmission of a token on the ring and to provide soft-error recovery in case of lost tokens, circulating frames or other difficulties. The capability is present in all ring stations.
monitor [3] 4. n. Software that monitors specific applications or the systems on which the applications rely. Monitors typically monitor information such as available disk space or application errors and compare the information to defined thresholds. When thresholds are exceeded, either system or network administrators can be notified, or an automated response can be performed.
monitor [4] 5. v. In the NetView Graphic Monitor Facility, to open a view that can receive status changes from Tivoli NetView for OS/390. Problem determination and correction can be performed directly from the view.
motherboard See system board.
motion video n. In multimedia, video that displays real motion.
mouse n. A commonly used pointing device that contains one or more buttons with which a user can interact with a computer system. For example, using a mouse button, a user can select objects or choices, initiate actions, or directly manipulate objects.
Moving Pictures Experts Group (MPEG) 1. n. A group that is working to establish a standard for compressing and storing motion video and animation in digital form. 2. n. The standard under development by this group.
MQSeries adj. Pertaining to a family of IBM licensed programs that provide message queuing services.
multicast 1. n. Transmission of the same data to a selected group of destinations. 2. n. A special form of broadcast in which copies of a packet are delivered to only a subset of all possible destinations.
Multiple Virtual Storage (MVS) See MVS..
multiplex v. To interleave or simultaneously transmit two or more messages on a single channel.
Multipurpose Internet Mail Extensions (MIME) n. An Internet standard for identifying the type of object being transferred across the Internet. MIME types include several variants of audio, graphics, and video.
multitasking n. A mode of operation that provides for concurrent performance, or interleaved execution of two or more tasks.
multitiered application n. An application that is deployed on more than one physical machine. A client/server application is a common multitiered application in which there are two tiers: the client tier (for example, the presentation and the graphical user interface) and the server tier (for example, the service and the database).
Musical Instrument Digital Interface (MIDI) n. A protocol that allows a synthesizer to send signals to another synthesizer or to a computer, or a computer to a musical instrument, or a computer to another computer.
MVS n. Multiple Virtual Storage. Implies MVS/390, MVS/XA, MVS/ESA, and the MVS element of the OS/390 operating system.
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