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Terminologies Simplified

Manchester Encoding A digital scheme used in Ethernet networks to encode data and timing signals in the same transmitted data stream. Manchester encoding uses a mid-bit-time transition for clocking, and a 1 denotes a high-level during the first half of the bit time.

Manufacturing Automation Protocol (MAP) A specification outlining the automation of tasks in a computer-integrated manufacturing or factory environment. MAP was originally formulated by General Motors to assist in procurement.

Manufacturing Message Service (MMS) A service used in automated production lines, enabling a computer application on a control machine to communicate with an application on a slave machine.

Mapped Conversation A conversation occurring between two transaction programs that are using the Advanced Program-to-Program Communication (APPC) Application Program Interface (API).

Markup Tag A formatting or inclusion tag in an editing program that serves as an instruction to a processing or reading program. A markup tag is not visible until the file is passed through an appropriate program. A familiar use of markup tags occurs in the Hypertext Markup Language (HTML) used to create Web pages, where tags represent document layout instructions and links to other places in a file. Markup tags are placed within angle brackets (< >).

Maximum-Receive Unit (MRU) An option in the Link Control Protocol (LCP). The MRU enables a sender to inform a peer that the sender can receive larger frames than specified in the default or to request that the peer send smaller frames.

Mean Time Between Failures (MTBF) A statistically derived average length of time (expressed in thousands or tens of thousands of hours), a computer system or component operates before failing.

Mean Time To Repair (MTTR) A statistically derived average length of time, it takes to repair a failing computer system or component.

Media The plural of medium, a term describing the physical paths over which communications flow (for example, copper wires, coaxial cables, or fiber-optic cables).

Media Access Control (MAC) One of two sublayers of the Data-Link Layer (layer 2 of the OSI Reference Model) that controls the use of network hardware and governs access to transmission media. This sublayer is defined in the Institute of Electronic and Electrical Engineers (IEEE) 802.x set of Local Area Network (LAN) standards. The other sublayer in the Data-Link Layer is the Logical Link Control (LLC) sublayer.

Media-Access Method A strategy on the Data-Link Layer (Layer 2) of the OSI Reference Model that network nodes use to access a network transmission medium. A common media-access method is Carrier Sense Multiple Access/Collision Detection (CSMA/CD).

Media Manager (MM) A NetWare database that tracks all peripheral storage devices and media attached to NetWare servers and enables applications to access or gain information from the devices and media. This database receives input/output requests from applications and converts them to messages compatible with the NetWare Peripheral Architecture (NPA).

Media-Set ID Identification information attached to electronic media to help identify their contents. The media-set ID is commonly used for back-up tape cartridges.

Medium-Attachment Unit (MAU) A device that detects collisions and injects bits onto the network. The MAU works on the Physical Layer (Layer 1) of the OSI Reference Model and complies with the Institute of Electronic and Electrical Engineers (IEEE) 802.3 standard.

Memory-Management Unit (MMU) The part of a computer microprocessor responsible for managing the mapping of virtual memory addresses to actual physical addresses. The MMU can be a separate chip (as was the case in early Intel or Motorola microprocessors) or part of the central processing unit (CPU) chip. NM