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MAC
(1) See Medium Access Control.
(2) See mandatory access control.
(3) See message authentication code.

MAC frame
A transmission frame that controls the operation of the IBM Token-Ring Network and any ring station operations that affect the ring.

machine characteristic
Values defined in the computer.

Machine Code
For i5/OS, the layered architecture below the machine interface (MI). The Machine Code is a proprietary system design that carries out many functions. These functions include but are not limited to storage management, pointers and addressing, program management functions, exception and event management, data functions, I/O managers, and security.

machine-generated data structure (MGDS)
(1) An IBM structured data format protocol for passing character data among the various Content Manager ImagePlus for OS/390 programs.
(2) Data extracted from an image and put into general data stream (GDS) format.

machine interface (MI)
The interface, or boundary, between the operating system and the Licensed Internal Code.

machine language
See computer language. See also computer instruction.

machine object
A program object that has no defined storage form; the object is defined internally to the machine. The machine aspect is not available to the user. See also data object.

machine storage pool
A storage pool used by the machine and certain highly shared programs, whose size is specified in the system value QMCHPOOL.

machine translation
A translation productivity tool that works by breaking down sentences or other text segments, analyzing them in context and then recreating their meaning in the target language. Machine translation works best on large volumes of well-written texts from narrow subject areas. This definition is from the Localisation Industry Standards Association (LISA) Glossary.

MAC protocol
See Medium Access Control protocol.

macro
(1) An instruction that when executed causes the execution of a predefined sequence of instructions in the source language. The predefined sequence can be modified by parameters in the macro. CICS RDM macros are assembler macros and are converted by the assembler.
(2) A program that performs a series of automated tasks on behalf of the user. A macro consists of three components: the trigger (when it acts), the search (what documents it acts on), and the action (what it does). Also called an agent.
(3) An XML script that defines a set of screens. Each screen includes a description of the screen, the actions to perform for that screen, and the screen or screens that can be presented after the actions are performed. A macro can be specified as one of the actions to be taken when a host screen matches the screen recognition criteria of a screen customization.
(4) In REXX, a program that performs certain operations, such as text editor operations, in applications.

macroinstruction
A single instruction that represents a set of instructions.

macro temporary store (MTS)
The SMP/E data set used to hold updated versions of macros that will not be placed in a target system library. They are stored during APPLY processing and deleted by ACCEPT or STORE processing.

MAC sublayer
See medium access control sublayer.

magnetic ink
An ink that contains particles of a magnetic substance whose presence can be detected by magnetic sensors.

magnetic ink character recognition
The identification of characters through the use of magnetic ink. See also optical character recognition.

magnetic storage device controller
The I/O controller card in the card enclosure that controls the operation of the disk, diskette, and tape devices.

magnetic stripe reader
A device, attached to a display station, that reads data from a magnetic stripe on a badge before allowing an operator to sign on.

magnetic tape drive
A technique for moving and controlling magnetic tape.

magnetic tape subsystem
A tape unit that includes the logic interface hardware necessary to operate with a system unit.

magnetic tape unit
A device for reading or writing data from or to magnetic tape.

mail
The distribution objects and documents referred to by a mail log.

mail-based initiation
A method of starting a Lotus Workflow job automatically by creating a document and mailing it to the application database (which must be set up as a mail-in database). An agent in the application database uses information in the e-mail message to create a binder and route it to the first activity. In form-based and mail-based initiation, the first user action - creating a document - isn't an "activity" within a Lotus Workflow process.

mailbox
A collection of pointers to message objects that are addressed to a single entity.

mail exchange record (MX record)
A record in the Domain Name System (DNS) that indicates which host handles mail for a particular domain.

mail inquiry
In Lotus Workflow, an e-mail message sent by the activity owner or job owner to get information from another person about an activity. Sending an e-mail inquiry doesn't affect routing for the job.

mail server framework (MSF)
A set of user exit points and application program interfaces (APIs) that embody an abstract design for solutions to a number of related communications problems.

mail session
A resource collection of protocol providers that authenticate users and control user access to messaging systems.

main branch
The starting branch of an element's version tree. The default name for this branch is main.

main distribution frame (MDF)
In the CallPath licensed program, a series of quick-connection blocks, supported on a frame, that allows trunk lines and telephones to be connected to the 9722 Redwood system.

main document
The document to be worked on in a Lotus Workflow activity. As its binder is routed from activity to activity, the main document can be based on different forms. Each binder contains only one main document.

main entry
A first-level or primary index entry in an index. Main entries are the key access points to the information, representing the main concepts in the information. They use both the product and the users' terminology.

main function
In the C language, a function that has the identifier main. Each program must have exactly one function named main. The main function is the first user function that gets control when a program starts to run.

mainline module
A sequence of instructions called by a program in the main path after it is compiled.

main program
(1) The first program unit to receive control when a program is run.
(2) The highest level program involved in a run unit.

main storage
(1) Program-addressable storage from which instructions and other data can be loaded directly into registers for subsequent execution or processing.
(2) See memory. See also auxiliary storage.

main storage database (MSDB)
In IMS, a root-segment database that resides in main storage and that can be accessed to a field level.

main storage dump (MSD)
(1) A process of collecting data from the system's main storage. It can be done automatically by the service processor as a result of a system failure, or it can be performed manually by the operator when there appears to be a system failure.
(2) An i5/OS logical partition failure that causes the contents of the partition's memory to be written to disk. This memory content is used for problem analysis.

main storage dump space
A section of storage reserved on the disk unit that is used as a place to save main storage for recovery and debugging.

main storage pool
A division of main storage, which allows the user to reserve main storage for processing a job or group of jobs, or to use the pools defined by the system. See also auxiliary storage pool.

main storage - TS queue
A dynamic storage area managed by CICS under the temporary storage facility. Data in main storage is not kept from one CICS run to the next. See also auxiliary storage - TS queue.

maintain system history program ( MSHP MSHP)
A program used for automating and controlling various installation, tailoring, and service activities for a VSE system.

maintenance
In Backup Recovery and Media Services, the tasks that must be performed on a routine basis to perform cleanup activities and other Backup Recovery and Media Services functions. Examples of maintenance are tape expiration, recovery analysis reports, and media movement.

maintenance point
A CICSPlex SM address space (CMAS) that is responsible for maintaining CICSPlex SM definitions in its data repository and distributing them to other CMASs involved in the management of a CICSplex.

maintenance window
A user-defined time period for running only required automatic maintenance activities. See also automatic maintenance.

main window
In VisualAge RPG, a window that is an immediate child of the desktop.

major/activity token
In OSI, the session-layer token that controls activities and major synchronize operations.

major node
In VTAM, a set of resources that can be activated and deactivated as a group.

major object descriptor block (MODB)
In CICSPlex SM, a control structure built by Kernel Linkage during initialization of a CICSPlex SM component that contains a directory of all methods that make up that component. The structure of the MODB is the same for all components.

major object environment block (MOEB)
In CICSPlex SM, a control structure built by Kernel Linkage during initialization of a CICSPlex SM component and pointed to by the MODB. MOEB stores information critical to a CICSPlex SM component and anchors data used by the component. The structure of the MOEB is unique to the component it supports.

major synchronization point
In OSI, a session-layer synchronization point that usually represents a logically significant piece of work. Major synchronization points are a confirmed service. See also minor synchronization point.

major synchronize
In OSI, a confirmed service provided by the session layer that enables peer application entities to synchronize the exchange of data. For example, an application entity can send data followed by a major synchronize request; its peer sends back a major synchronize response, which indicates that it has received all of the data that was sent up to the major synchronize request. The major synchronization function also marks a recovery point in the data stream. See also minor synchronize.

major tick
In Business Graphics Utility, a mark on an axis that denotes character grid units on a chart. See also minor tick.

make
In VisualAge RPG, the process by which all of the components are compiled and assembled to create a VRPG application.

MAN
See metropolitan area network.

Managed Bean (MBean)
In the Java Management Extensions (JMX) specification, the Java objects that implement resources and their instrumentation. MBeans must follow the design patterns and interfaces defined in the instrumentation level of the JMX specification. This ensures that all MBeans provide the instrumentation of managed resources in a standardized way. MBeans are manageable by any JMX agent, but they can also be managed by non-compliant agents that support the MBean concept.

managed mode
Describes an environment in which connections are obtained from connection factories that the J2EE server has set up. Such connections are owned by the J2EE server.

managed node
(1) A node with an application server and a node agent that belongs to a cell.
(2) In a Tivoli environment, a computer system on which Tivoli Management Framework is installed.

managed object
In OSI, a resource that is subject to management--such as a layer entity, a connection, or a line--as viewed from a systems management perspective.

managed query
A query that is subject to the Query Patroller thresholds and parameters that control how a query is handled, for example, whether it is allowed to run, queued, or rejected. See also intercepted query, held query, query status.

managed resource
(1) An entity that exists in the run-time environment of an IT system and that can be managed.
(2) In a Tivoli environment, a database object that represents a resource and is governed by policies.

managed system
A system that is being controlled by a given system management application; for example, a system managed by an HMC or by iSeries Navigator.

Managed System Services
An IBM licensed program that enables a system to be managed by a central site ES/9000 system running the IBM NetView Distribution Manager program. Managed System Services enables objects and program temporary fixes (PTFs) to be sent or retrieved, PTFs to be applied, programs to be run, and the central site system to control an initial program load (IPL) of the system.

managed target
A plug-in application that requires the support of user accounts from Tivoli Identity Manager.

Management Central
A suite of systems management functions that is an integrated part of iSeries Navigator. Management Central provides the base for managing multiple systems.

management class
(1) The term used in the APIs for migration policy.
(2) In storage management, a policy object that users can bind to each file to specify how the server manages the file. The management class can contain a backup copy group, an archive copy group, and space management attributes. The copy groups determine how the server manages backup copies or archive copies of the file. The space management attributes determine whether the file is eligible to be migrated from the space manager client nodes to server storage and under what conditions the file is migrated.

management collection
An object within the OS/400 operating system that includes the data for a number of collections. The collections begin when the collector is started and continue until the collection is either ended or cycled. The system-recognized identifier for the object type is *MGTCOL.

management domain
In OSI X.400, a set of one or more message transfer agents and zero or more user agents that make up a system capable of handling messages and is managed by either an administration or private company.

management information
In OSI, information--associated with a managed object--that is operated on by management protocols to control and monitor that object.

Management Information Base ( MIB MIB)
(1) A collection of objects that can be accessed by means of a network management protocol.
(2) A database containing the information pertinent to network management. The database is conceptually organized as a tree.
(3) In System Manager, units of managed information that specifically describe an aspect of a system, such as the system name, hardware number, or communications configuration. A collection of related MIB objects is defined as a MIB.

Management Information Base variable (MIB variable)
A managed object that contains pertinent management information, which is accessible as defined by the access mode. The MIB variable is defined by a textual name and the corresponding object identifier, syntax, access mode, and status, as well as a description of the semantics of the managed object.

management protocols
In OSI, protocols for use in systems management.

management region
The set of managed objects on a particular map that defines the extent of the network that is being actively managed. The management region may vary across Tivoli NetView maps.

management services (MS)
In SNA, one of the types of network services in control points and physical units. Management services is the service provided to assist in the management of SNA networks, such as problem management, performance and accounting management, configuration management, and change management.

manager
(1) The part of a distributed management application that issues requests and receives notifications; that is, uses the services of one or more agents.
(2) See managing process.

manager access
An access level that gives users permission to compose, read, and edit any documents; modify the access control list, database icon, About and Using documents, and all design elements; define replication settings; and delete the database. Servers that have this access level can replicate documents, the access control list, the database icon, About and Using documents, all design elements, and replication settings; and, if they have delete access, they can replicate deletions.

manager list
In OSI, a list that an agent maintains of the managing processes that are--or are eligible to become--managers of that agent.

manager node
In OSI, a node that provides a managing process.

managing process
In OSI, the part of a systems management application that monitors and controls the resources of an agent process. In OSI Communications Subsystem, the managing process can send operator commands to--and receive event reports from--its agent processes.

mandatory access control (MAC)
A mechanism that enforces the corporate security policy and prevents a user from making information available arbitrarily.

mandatory entry field
A field in which an operator must enter at least one character.

mandatory fill field
A field that a user must leave blank, or must fill in completely.

mandatory place
A shared place, either a public place or a restricted place, in which all portal users must be members. Only portal administrators can designate a shared place to be a mandatory place. Because membership is automatic and required, portal users cannot join or leave mandatory places.

manifest
(1) A special file that can contain information about the files packaged in a JAR file. (Sun)
(2) A shipment confirmation that may contain tracking identification information.
(3) A text file that specifies the properties of a diagnostic guide or a tool.

manual answer
In data communications, a line type that requires operator actions to receive a call over a switched line. See also automatic answer.

manual call
In data communications, a line type requiring operator actions to place a call over a switched line. See also automatic calling.

manual connection
A virtual private network (VPN) connection in which all of the parameters of a manual connection must be set up manually. Manual connections do not automatically refresh the keys that maintain data security. See also dynamic connection.

manual load
In Q replication, a load process in which the user loads data into a target table and then notifies the replication program when the table is loaded. See also automatic load.

Manufacturing Automation Protocol (MAP)
In OSI, a specification developed by industrial users to provide a common set of protocols to allow communications between computers and factory floor equipment in the manufacturing environment. It is based on a subset of the open systems interconnection (OSI) standard.

manufacturing refresh
An update of an existing product for which the product media are completely replaced. A product refresh contains new functions and cumulative fixes. It is intended for new customers who want to install the current level of the product. See also interim fix, refresh pack.

MAP
(1) See Manufacturing Automation Protocol.
(2) See mobile application part.

map
(1) An entity that contains the Java code to specify how to transform attributes from one or more source business objects to one or more destination business objects. A map either converts from an application-specific business object to a generic business object (outbound map) or from a generic business object to an application-specific business object (inbound map).
(2) A named collection of objects, symbols, submaps, and their relationships, all of which represent the network topology.
(3) In BMS, a format established for a page or a portion of a page, or a set of screen format descriptions. A map relates program variables to the positions in which their values appear on a display device. A map contains other formatting information such as field attributes. A map describes constant fields and their position on the display, the format of input and output fields, the attributes of constant and variable fields, and the symbolic names of variable fields.
(4) In Business Integration Modeler, a map is a specialized task that transforms data from one structure to another. A map can be used to specify how to transform input into output.
(5) In the EJB development environment, the specification of how an enterprise bean's container-managed persistent fields correspond to columns in a relational database table or other persistent storage. The map is used to generate deployment code.
(6) To correlate fields in a Java class to columns in a relational database table or other persistent storage.

map definition
Definition of the size, shape, position, potential content, and properties of BMS map sets, maps, and fields within maps, by means of macros. See also field definition macro, map definition macro, map set definition macro.

map definition macro (DFHMDI)
In BMS, a macro that defines a map within the map set defined by the previous DFHMSD macro. See also map definition.

Map Designer
A WebSphere business integration code-generation tool with which you create and edit map definitions to define transformations between source and destination business objects.

mapped address
A bidirectional mapping of one address to another.

mapped conversation
(1) In advanced program-to-program communications (APPC), a temporary connection between an application program and an APPC session in which the system provides all the information on how the data is formatted. See also basic conversation.
(2) In APPC, a conversation between two transaction programs (TPs) using the APPC mapped conversation API. In typical situations, end-user TPs use mapped conversation, and service TPs use basic conversations. Either type of program can use either type of conversation. See also basic conversation.

mapping
(1) A representation of one thing to another.
(2) The process of transforming (or mapping) data from one application-specific format to another.
(3) In BMS, the process of transforming field data to and from its displayable form.

mapping cardinality
The granularity of the way that message elements are mapped from message source to message target. For example, one source element to one target element, or many source elements to one target element.

mapping object
(1) A function of AFP Utilities that maps a database field value to an object name.
(2) An object that passes values to the IBM-supplied mapping program. It is used to customize the PDF subsystem without writing a mapping program. See also mapping program, PDF subsystem.

mapping program
An exit program used to interpret routing tags, to specify the subject of an e-mail, to add text to the beginning of an e-mail, to specify the path to store the PDF stream file, and more. See also intelligent routing, PDF subsystem, mapping object.

mapping table
An object that contains a set of hexadecimal characters used to map data from one character set and code page to another. For example, unprintable characters can be mapped to blanks, and lowercase alphabetic characters can be mapped to uppercase characters.

map set
In basic mapping support (BMS), one or more maps combined in a map set. The effects of this combination are to reduce the number of entries in the PPT, and to load simultaneously all maps needed for one application.

map set definition macro (DFHMSD)
A macro that is used to define a set of BMS maps. See also map definition.

map set suffix
In BMS, a suffix relating different versions of a map set to different terminal models or partitions. This allows you to format the same data differently on different screen types, in response to the same programming request.

margin A
The margin between the 7th and 8th character positions of a reference format for a COBOL source program line.

margin B
The margin between the 11th and 12th character positions of a reference format for a COBOL source program line.

margin C
The margin between the 6th and 7th character positions of a reference format for a COBOL source program line.

margin L
The margin immediately to the left of the leftmost character position of a reference format for a COBOL source program line.

margin R
The margin immediately to the right of the rightmost character position of a reference format for a COBOL source program line.

margin text
Notes written in the margins on the top, bottom, left, or right of a document.

marker
In the GDDM function, a symbol centered on a point. Line charts may use markers to indicate the plotted points.

marker bar
The gray border at the left of the editor area of the workbench, where bookmarks and breakpoints are shown.

marketing event
In WebSphere Commerce, any event within the system that is considered to be significant for the purposes of marketing. Most marketing events are directly driven by customer behavior. Examples include catalog browsing, navigation, and shopping cart activity.

marketing manager
A defined role in WebSphere Commerce that monitors, analyzes, and understands customer behavior. The marketing manager also creates and modifies customer segments for targeted selling and creates and manages campaigns.

marketplace
A business-to-business electronic commerce Web site in which those organizations granted access to the site are presented with a unified view of the products and services being traded on that site. They are also provided with a variety of trading mechanisms to facilitate trade among themselves.

marking
In QoS, the process of setting the bits in the Internet Protocol (IP) type-of-service byte. This is primarily a mechanism that is used in differentiated services. As an example, in-profile packets could be marked with one differentiated services code point, while out-of-profile packets are marked with another code point.

markup language
A notation for identifying the components of a document to enable each component to be appropriately formatted, displayed, or used.

marshaling
See serialization.

marshall
The conversion of an object into a data stream for transmission over a network.

mask
A pattern or template that is applied to an Internet Protocol (IP) address to specify which bits are significant and which bits are irrelevant.

masking character
A character used to represent optional characters at the front, middle, and end of a search term. Masking characters are normally used for finding variations of a term in a precise index.

masquerade NAT
A TCP/IP function that allows a user to translate multiple Internet Protocol (IP) addresses to another single IP address. Masquerade NAT is used to hide one or more IP addresses on an internal network behind an IP address that will be made public. Traffic can initiate from the private internal addresses only.

mass delete
The deletion of all rows of a table.

massively parallel processing (MPP)
The coordinated execution of a single request either by multiple single-processor computers in a shared-nothing environment (in which each computer has its own memory and disks); or by symmetric multiprocessor (SMP) computers (in which multiple processors in each computer share memory and disks). Both environments require that all computers are linked together in a high-speed network.

master
In a multi-MVS or VSE MRO XRF configuration, a region that issues commands to dependent regions at takeover time. See also coordinator.

master build descriptor
In EGL, a build descriptor part whose options cannot be overridden.

master catalog
The main catalog containing all products, SKUs, descriptions, and standard pricing for each product. Each product belongs to a single category. See also online catalog.

master file
A collection of permanent information, such as a file of customer addresses.

master index
An index made up of entries from two or more components or deliverables. Examples are master indexes for a product information center, a solution containing more than one product, or a PDF library.

master name server
A name server that provides secondary name servers with domain data.

master profile
In iSeries Access family, a file that contains the session profiles and keyboard profiles for a user's workstation function session.

master replica
In ClearCase MultiSite, the master replica of a ClearCase object is the only replica at which the object can be modified or instances of the object can be created.

masters catalog
In Lotus Learning Management System, the service that lists and manages course masters.

mastership
In ClearCase MultiSite, the ability to modify an object or to create instances of a type object.

masters manager
In Lotus Learning Management System, a person who creates classroom and learning event masters through the Administrator interface; a person who manages the sum of learning content in the system.

master sort table
A system-supplied table that contains sort information required for sorting double-byte characters. This table is maintained by the character generator utility function of the Application Development ToolSet licensed program.

master table
In SQL replication, specifically in update-anywhere replication, the original source table for data in the replica table. If replication conflict detection is enabled, changes made to the master table are retained, whereas changes made to the replica table are rejected. See also conflict detection, replica table, update-anywhere replication.

master terminal
(1) The IMS logical terminal that has complete control of IMS resources during online operations.
(2) In CICS, the terminal at which a designated operator is signed on.

master terminal functions
A set of functions that allow a user to dynamically control and alter the operation of a CICS system.

master terminal operator (MTO)
(1) In a z/OS or OS/390 environment, the person who is responsible for operating the IMS control center.
(2) Any CICS operator authorized to use the master terminal functions transaction (CEMT).

matched credit
A credit payment that has been matched with a credit advice. Such credits are not considered when calculating the expected end-of-day position of their corresponding channels. See also full matching, partial matching.

match fields
In RPG primary or secondary multifile processing, fields within a record type that are to be used for checking the order of a single file, or for matching records of one file with those of another file.

matching record indicator (MR indicator)
An indicator used in calculation or output specifications to indicate operations that are to be performed only when records match in primary and secondary files.

matching rule
A rule that describes how to perform a comparison.

match level
In RPG, the value (M1 through M9) assigned to the match field. The match level identifies fields by which records are matched during primary or secondary multifile processing.

materialize
(1) To put rows from a view or nested table expression into a work file for additional processing by a query.
(2) To place an LOB value into contiguous storage. Because LOB values can be very large, DB2 Universal Database for z/OS and OS/390 avoids materializing LOB data until doing so becomes absolutely necessary.

materialized query table (MQT)
A table whose definition is based on the result of a query and whose data is in the form of precomputed results that are taken from the table, or tables, that the materialized query table definition is based on. See also automatic summary table.

matrix
(1) An arrangement in rows and columns.
(2) An arrangement of rows and columns used for organizing related items in a view. See also Attribute Matrix, Traceability Matrix.

MAU
See multistation access unit.

maxcon
The number of conversations that can be active at one time. The system asks you to define this number when you set up NAT masquerade rules. The default value is 128. Maxcon only pertains to Masquerade NAT rules.

maximize
A choice that, when selected, enlarges the window to its largest possible size.

maximum transmission unit (MTU)
The largest possible unit of data that can be sent on a given physical medium in a single frame. For example, the maximum transmission unit for Ethernet is 1500 bytes.

Mb
See megabit.

MB
See megabyte.

MBCS
See multibyte character set.

MBean
See Managed Bean.

MBean provider
A library containing an implementation of a Java Management Extensions (JMX) MBean and its MBean Extensible Markup Language (XML) descriptor file.

MBO
See message backout table.

Mbps
See megabits per second.

MCA
(1) See message channel agent.
(2) See Micro Channel architecture.

MCB
See message control block.

MCI
See message channel interface.

MCP
See message control program.

MCSL
See Monitoring Collection Specification Language.

MCT
See monitoring control table.

MCU
See multipoint control unit.

MD5
A type of message algorithm that converts a message of arbitrary length into a 128-bit message digest. This algorithm is used for digital signature applications where a large message must be compressed in a secure manner.

MDC table
See multidimensional clustering table.

MDF
(1) See multiple device file.
(2) See main distribution frame.

MDH
See migration data host.

MDSP
See Mobile Data Synchronization Protocol.

MDSS
See Mobile Data Synchronization Service.

MDT
See modified data tag.

mean time to recovery (MTTR)
The average time it takes to make a system operational after a failure.

mean time to repair (MTTR)
A measure of serviceability indicating the expected time required to repair a unit after failure.

measurement
See metric. See also service level objective.

measurement group
A grouping or classification of measurement types. This grouping can represent any of the characteristics of the measurement, including grouping the measurements into broad classes, such as performance or availability.

measurement source
The source application where a measurement originates. Performance and availability measurements are collected by the source application and written to a central data warehouse for later processing.

measurement type
The class or meaning of a particular measurement. The measurement type identifies what a particular measurement represents, such as PERCENTUSED for the amount of disk space that is used on a particular component. For each measurement type there are many measurements recorded. Measurement types remain the same across different components, while the measurements themselves are related to only one component.

mechanism
(1) A specific algorithm or operation (such as a queueing discipline) that is implemented in a node to realize a set of one or more per-hop behaviors.
(2) In the Reusable Asset Specification (RAS), a special kind of pattern, providing a common solution to a common problem in a given context. A mechanism is a design pattern that applies to a society of classes. It can be applied to any and all layers of the system must be represented with a parameterized collaboration. There must be at least one role on the collaboration that is bound to a concrete element. Mechanisms are not fully, but partially implemented solutions that contain at least one unbound role.

media
(1) Magnetic disks, magnetic tapes, compact discs (CDs), and digital video disks (DVDs).
(2) In Backup Recovery and Media Services, an individual physical tape cartridge or tape reel, or removable storage device available for use by the server. This media is grouped into media classes for management, tracking, and statistical analysis.

media access method
The method for determining which device has access to the transmission medium at any time.

media archiver
A physical device that is used for storing audio and video stream data. The VideoCharger is a type of media archiver. See also storage system.

media class
In Backup Recovery and Media Services, a user-defined name used to identify the type and characteristics of the physical media to be managed as a group for backup, archive, or recovery operations. Each media class is distinguished by attributes, such as format or capacity, that are used by the server.

media image
In WebSphere MQ on UNIX systems and WebSphere MQ for Windows, the sequence of log records that contain an image of an object. The object can be re-created from this image.

media inventory
In Backup Recovery and Media Services, a library that contains information about media that has been enrolled in Backup Recovery and Media Services. The media inventory contains information such as volume serial identifier, expiration date, creation date, and location. Media in the media inventory is used for backup, archive, and recovery operations.

medialess
Pertaining to a personal computer or workstation that does not have a diskette or tape drive or a hard disk.

medialess programmable workstation
A programmable workstation that does not contain a diskette or tape drive or a hard disk. Cooperative processing is done through a shared folder on the server.

media library device (MLD)
A tape storage device that contains one or more tape drives, tape cartridges, and a part (carriage and picker assembly) for moving tape media between the cartridge storage slots and the tape drives.

media management
In Backup Recovery and Media Services, the overall control, cataloging, and tracking of removable media by status, storage location, container placement, and contents by volume from creation to expiration. Backup Recovery and Media Services tracks only enrolled volumes. Tapes and other media are managed by media class and individual volumes within the class. Both active and expired media are tracked by volume serial number.

media origin
One of the four corners of the physical medium (usually paper) where printing begins.

media policy
In Backup Recovery and Media Services, a policy that defines the default values used for management of a media class. A user can have multiple media policies (one for each media class) to define such things as the move policy used for this media class, the type of retention, the use of save files, and the number of copies to be made. Values for a media policy are inherited from the system policy and can be overridden by the media policy or by the user at the control group level.

media pool
In Backup Recovery and Media Services, a grouping of media by similar characteristics such as by tape density or tape capacity. A media pool is used to help track media and protect the active data on the media. Synonymous with media class.

media server
An AIX-based component of the Content Manager system that is used for storing and accessing video files.

media set
(1) In software distribution and installation, a multivolume CD-ROM, CD-R, or tape group created for the purpose of distributing a selection of software to customers for installation on to the system. Some media sets, for example, a system software release upgrade media set, may consist of a collection of smaller media sets, each containing a specialized selection of the Licensed Internal Code, licensed programs, the operating system, and program temporary fixes needed to operate the system and use it to do business.
(2) In Backup Recovery and Media Services, a multivolume tape group created as a result of a backup operation or archive operation. Media sets are managed as a group to provide consistent management of single and multivolume output and to provide integrity in cases where an individual volume in a media set is expired in advance of the remaining volumes.

medium
The disk, tape, or diskette used to store information in a save or restore operation.

Medium Access Control ( MAC MAC)
(1) In LANs, the sublayer of the data link control layer that supports medium-dependent functions and uses the services of the physical layer to provide services to the logical link control (LLC) sublayer. The MAC sublayer includes the method of determining when a device has access to the transmission medium. http://www-306.ibm.com/software/network/commserver/linux/v6010/gloss02.htm
(2) For local area networks, the method of determining which device has access to the transmission medium at any time.

Medium Access Control protocol (MAC protocol)
In a local area network, the protocol that determines which device has access to the transmission medium at a given time.

medium access control sublayer (MAC sublayer)
One of two sublayers of the ISO Open Systems Interconnection data link layer proposed for local area networks by the IEEE Project 802 Committee on Local Area Networks and the European Computer Manufacturers Association (ECMA). It provides functions that depend on the topology of the network and uses services of the physical layer to provide services to the logical link control (LLC) sublayer. The OSI data link layer corresponds to the SNA data link control layer.

medium attachment unit
See transceiver.

meeting
In Sametime, a virtual gathering of two or more people to do work. It can include, but is not limited to, chat, IP audio/video, screen sharing, shared whiteboard, or telephone conference calls.

meeting details
In Sametime, a list that displays information that is entered when a meeting is scheduled. This information initially includes the moderator's name, the date and time of the meeting, and any file attachments that will be used in the meeting. After the meeting has taken place, the meeting details displays the recording of the meeting.

meeting services
In Sametime, data-sharing services that support screen sharing and the shared whiteboard.

meeting status
In Sametime, the current status of an online meeting as displayed in the list of meetings. The status could be active, scheduled, or finished. See also active meeting, scheduled meeting.

meeting type
One of three pre-defined Sametime meeting designations that assign the level of interaction available for the meeting. The available pre-defined meeting types are: collaboration, moderated presentation or demo, and broadcast presentation or demo. See also instant meeting.

meet-in-the-middle mapping
An approach for mapping enterprise beans to database tables in which enterprise beans and database schema are created simultaneously but independently.

megabit ( Mb Mb)
(1) For disk storage capacity and communications volume, 1 000 000 bits.
(2) For processor storage, real and virtual storage, and channel volume, 2 to the power of 20 or 1 048 576 bits.

megabits per second (Mbps)
See also kilobits per second.

megabyte (MB)
(1) A unit of measure for storage capacity. For main storage, 1 MB equals 1 048 576 bytes (1024 x 1024); for auxiliary storage (disk, diskette, and tape), 1 MB equals 1 000 000 bytes (1000 x 1000).
(2) 1,048,576 bytes in decimal notation when referring to processor storage; in all other cases, 1,000,000 bytes (for example, for disk storage capacity and transmission rates).
(3) For processor storage, real and virtual storage, and channel volume, 2 to the power of 20 or 1048576 bytes.
(4) For processor storage and real and virtual memory, 1 048 576 bytes.

member
(1) A person, group, or organization known to the system. A member can be a user, an organization, an organization unit, or a member group. A member may act as a customer or an administrator, or may own entities. A member must first become a member of the marketplace before becoming a user.
(2) In iSeries, one of several different sets of data, each with the same format, within one database file.

member function
C++ operators and functions that are declared as members of a class. A member function has access to the private and protected data members and member functions of an object of its class. Member functions are also called methods.

member group
A group that is used to implement role-based control in WebSphere Commerce. The type of member group indicates its intended usage. A customer group is for general use, while an access group is for access control purposes.

member name
The XCF identifier for a particular DB2 Universal Database for z/OS and OS/390 subsystem in a data sharing group.

member scope
In a data sharing environment, the scope of a command that affects only the DB2 databases for which it is issued. See also group scope.

membership
The state of being a portal user and a place member. Membership in the portal is controlled by the administrator during the installation and set up of portal servers. Membership in places is controlled by a place manager, who determines the level of access for each place member: participant, place designer, or place manager.

member state
In DB2 Universal Database for z/OS and OS/390, the state of the DB2 member (subsystem) of the data sharing group.

memory
Program-addressable storage from which instructions and other data can be loaded directly into registers for subsequent running or processing. See also auxiliary storage.

memory leak
The effect of a program that maintains references to objects that are no longer required and therefore need to be reclaimed.

memory pool
A logical division of memory (storage) that is reserved for processing a job or group of jobs. Synonymous with main storage pool.

MEMS
See Micro-Electric Mechanical System.

mentor
In LikeMinds Recommendation Engine, a specially designated user who has visited an e-commerce application a number of times, and whose profile is among the most similar to that user relative to all the users who browse that Web site.

menu
(1) A displayed list of available functions for selection by the operator.
(2) A displayed list of items from which a user can make a selection.

menu bar
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.

menu bar field
In DDS, a panel element that contains a numeric field containing one or more menu-bar choice keywords.

menu bar separator
In DDS, a panel element that contains a horizontal line that appears directly below a menu bar.

menu bar switch key
A key that alternates the cursor between the menu bar and that application display.

menu file
A text file with specific syntax that is used to add menu commands to any RequisitePro menu. Menu files typically have an MNU or TXT file extension. Menu files are referenced using the Add-ins command on the Tools menu. The commands appear on the RequisitePro menus in the order in which they are specified in the menu file.

menu security
A function of the operating system that controls which system resources are available to users. Menu security restricts a user to a single menu or a sequence of menus that are defined in the user profile.

menu shortcut
See keyboard shortcut.

merchandising association
An association between two catalog items for the purpose of a sales activity. For example, a camera might have a "requires" merchandising association with a set of batteries, and a dictionary might have a "goes with" merchandising association with a thesaurus. See also accessory.

merge
(1) To insert records throughout a single output file.
(2) To update and insert new content into a table.
(3) A process element that recombines multiple processing paths, usually after a decision. A merge brings several alternative paths together.
(4) To combine overrides for a file from the first call level up to and including a greater call level, producing the override to be applied when the file is used.

merge file
In COBOL, the temporary file that contains all the records to be merged by a MERGE statement. The merge file is created and can be used only by the merge function.

MERVA for ESA
An IBM licensed program that is a message queuing and routing system that allows a financial institution to process all kinds of financial messages. Access to the SWIFT Transport Network (STN) is included as a standard communication link.

MERVA Link
A MERVA component that can be used to interconnect several MERVA systems.

MES
See miscellaneous equipment specification.

mesh-connected session network
A configuration where every network node has a control point-to-control point session to every other network node. As the number of network nodes increases, the number of CP-to-CP sessions increases dramatically.

mesh network
A self-forming, self-healing, self-routing wireless mobility network. http://www-1.ibm.com/services/us/index.wss/mp/imc/xt/a1001345/2?cntxtId=a1000450

message
(1) A formatted transfer unit used to exchange control or payment information.
(2) A set of data that is passed from one application to another. A message can be modeled by a message definition, which describes the structure and content of the message. Messages must have a structure and format that is agreed by the sending and receiving applications.
(3) In system programming, information intended for the terminal operator or system administrator.
(4) In OSI Message Services, a piece of electronic mail in the format of the X.400 CCITT standard. An X.400 message can be a document, note, message, or file.
(5) In Web Services Description Language (WSDL), a single piece of information moving between the invoker and the service that describes which operations the service provides. A message consists of logical parts, each of which is associated with a definition within some type of system.
(6) A communication sent from a person or program to another person or program.

message area
In BMS, the area of a screen used to send instruction messages to assist the operator in processing a transaction. This area should be separate from the application data area to allow communication with the operator, without disturbing the application data. The message area is normally the bottom one or two lines of the screen.

message authentication code ( MAC MAC)
(1) In computer security, a value that is a part of a message or accompanies a message and is used to determine that the contents, origin, author, or other attributes of all or part of the message are as they appear to be.
(2) In Cryptographic Support, the first 4 bytes from the last 8-byte block of ciphertext produced when encrypting a message using cipher block chaining, that is added to the end of the plaintext message from which it was created and used to detect whether the message was changed during transmission.

message authentication key
In Cryptographic Support, a data encrypting key used to encrypt data to produce a message authentication code.

message backout table (MBO)
In the restart data set, a summary table that contains an entry for each terminal for which logged or journaled message or message resynchronization records were written to the restart data set. Data in this table is available to user-written exit programs.

message body
The part of the message that contains the message payload. See also message header.

message box
A secondary window that displays a message about a particular situation or condition.

message broker
See broker. See also message flow.

message cache
A temporary storage queue with a DATAID of DFHMxxxx, where xxxx is the identification of a logical unit, into which CICS reads messages (for message-protected tasks only) during emergency restart. A user-written enquiry program run after emergency restart can read the contents of message caches. CICS does not read or purge message caches.

message category
A group of messages that are logically related within an application.

Message Center
An IBM product that uses DirectTalk's voice processing capabilities to provide a wide range of voice mail, fax, and e-mail functions.

message channel
In distributed message queuing, a mechanism for moving messages from one queue manager to another. A message channel comprises two message channel agents (a sender at one end and a receiver at the other end) and a communication link.

message channel agent (MCA)
A program that transmits prepared messages from a transmission queue to a communication link, or from a communication link to a destination queue. See also Message Queue Interface.

message channel interface (MCI)
The WebSphere MQ interface to which customer- or vendor-written programs that transmit messages between a WebSphere MQ queue manager and another messaging system must conform. A part of the WebSphere MQ Framework.

message control block (MCB)
The definition of a message, screen panel, net format, or printer layout made during customization of MERVA.

message control program (MCP)
In ACF/TCAM, a specific implementation of an access method, including I/O routines, buffering routines, activation and deactivation routines, service facilities, and SNA support.

message data set
The message data set is used principally to pass messages about the current state of specific resources from the active system to the alternate system. It is also used for the secondary surveillance signals of the active, alternate, or both CICS systems, when the control data set is unavailable for this purpose, either because the last write has not completed yet or because of I/O errors.

message definition
A logical description of a message. A message definition is a structured collection of simple elements.

message definition file
A file that contains the messages, elements, types, and groups that make up a message set.

message delivery preference
The subscriber's choice of whether voice mail is stored as voice mail only, as e-mail only, or as both voice mail and e-mail.

message delivery type
The format in which a voice message is delivered.

message descriptor
Control information describing the message format and presentation that is carried as part of a WebSphere MQ message. The format of the message descriptor is defined by the MQMD structure.

message dictionary
A data structure that describes all the messages in a message set in a form suitable for deployment to a broker.

message digest
A hash value or a string of bits resulting from the conversion of processing data to a number.

message domain
(1) Major component of CICS. It is a repository for CICS messages and it handles the sending of messages to transient data destinations or to the console. It also provides an interface for returning the text of a message to the caller.
(2) A grouping of messages that share certain characteristics. A message domain has an associated parser that interprets messages that are received and generated by a broker. WebSphere Business Integration Message Broker supports messages in the BLOB domain, JMS domain, MRM domain, and XML domain. User-defined parsers can be used to support messages that do not conform to the supported domains.

message-driven bean
An enterprise bean that provides asynchronous message support and clearly separates message and business processing.

message envelope
The information associated with a message aside from attachments and recipients.

message exit
A type of channel exit program that is used to modify the contents of a message. Message exits usually work in pairs, one at each end of a channel. At the sending end of a channel, a message exit is called after the message channel agent (MCA) has got a message from the transmission queue. At the receiving end of a channel, a message exit is called before the message channel agent (MCA) puts a message on its destination queue.

message file
(1) In CICS, the file holding the text of all CICS messages.
(2) An object that contains message descriptions. The system-recognized identifier for the object type is *MSGF.

message flow
A sequence of processing steps that execute in the broker when an input message is received. Message flows are defined in the workbench by including a number of message flow nodes, each of which represents a set of actions that define a processing step. The connections in the flow determine which processing steps are carried out, in which order, and under which conditions. See also message broker, subflow.

message flow control
A distributed queue management task that involves setting up and maintaining message routes between queue managers.

message flow node
A processing step in a message flow. A message flow node can be either a built-in node, a user-defined node, or a subflow node. See also node.

message flow node connection
An entity that connects the output terminal of one message flow node to the input terminal of another. A message flow node connection represents the flow of control and data between two message flow nodes.

Message Format Service ( MFS MFS)
(1) A MERVA direct service that formats a message according to the medium to be used, and checks it for formal correctness.
(2) An editing facility that allows application programs to deal with simple logical messages instead of device-dependent data, thus simplifying the application development process.

Message Format Service control block (MFS control block)
In MFS, the representation of a message or format that is stored in the IMS.FORMAT library and called into the MFS buffer pool as needed for online execution.

message group
A group of logical messages. Logical grouping of messages allows applications to group messages that are similar and to ensure the sequence of the messages.

message handling system (MHS)
In OSI X.400, a collection of message transfer agents and user agents that provide support for sending and receiving messages.

Message Handling System (MHS)
An X.400 MHS standard, electronic system for exchanging messages among store-and-forward mail systems. In ISO terminology, X.400 is called MOTIS (Message-Oriented Text Interchange System). The goal of the standard is to provide compatibility among multi-vendor products and interfaces as well as public and private message services.

message header
The part of a message that specifies the sender and receiver of the message, the message priority, and the type of message. See also message body.

message help
More information about a message, such as the message type, severity, and date and time sent.

message ID
See message identifier.

message identifier (message ID)
(1) A 7-character code that identifies a predefined message, and is used to get the message description from a message file.
(2) A tag attached to a message that uniquely identifies that message across all IBM products. This definition is from the corporate message guideline.

message input descriptor (MID)
The MFS control block that describes the format of the data presented to the application program. See also message output descriptor.

Message Integrity Protocol (MIP)
In MERVA Link, the protocol that controls the exchange of messages between partner ASPs. This protocol ensures that any loss of a message is detected and reported, and that no message is duplicated despite system failures at any point during the transfer process.

message line
An area on the display where messages are displayed.

message model
A definition of a message format that is used by applications. Message models are defined in the workbench.

message object
An abstraction of the data structures or system objects that store mail server framework message information.

message output descriptor (MOD)
The MFS control block that describes the format of the output data produced by the application program. See also message input descriptor.

message parser
A program that interprets the bit stream of an incoming message and creates an internal representation of the message in a tree structure, and that regenerates a bit stream for an outgoing message from the internal representation.

message performance option
The improvement of ISC performance by eliminating syncpoint coordination between the connected systems.

message priority
In WebSphere MQ, an attribute of a message that can affect the order in which messages on a queue are retrieved, and whether a trigger event is generated.

message-processing function
The various parts of MERVA used to handle a step in the message-processing route, together with any necessary equipment.

message processing node
(1) See message flow node. See also node.
(2) A node in a message flow that represents a processing step. A message processing node can be either a primitive or a subflow node.

message processing program ( MPP MPP)
(1) An IMS online program that can access DB2 Universal Database for z/OS and OS/390 databases, full-function databases, data entry databases, and main storage databases.
(2) A program that processes or otherwise responds to messages received from terminals.

message protection
A recovery and restart function provided by CICS. It logs input and output messages for VTAM terminals and enables the messages to be recovered following a system failure.

message protocol data unit (MPDU)
In OSI, the elements in Protocol 1 (P1) that are used between message transfer agents (MTAs).

message queue
(1) A list on which messages are placed when they are sent to a user ID or device description. The system-recognized identifier for the object type is *MSGQ.
(2) In interprocess communications, a mechanism that allows a process to communicate with other processes by sending messages to a process, receiving messages from a process, or performing control operations on a process.

Message Queue Interface (MQI)
The programming interface provided by WebSphere MQ queue managers. The programming interface allows application programs to access message queuing services. See also Application Messaging Interface, Java Message Service, message channel agent.

message queue management (MQM)
In MQSeries for Compaq NonStop Kernel, a facility that provides access to PCF command formats and control commands to manage queue managers, queues, and channels.

Message Queue Manager (MQM)
An IBM licensed program that provides message queuing services. It is part of the MQSeries set of products.

message queuing
A programming technique in which each program within an application communicates with the other programs by putting messages on queues.

message reference key
A key assigned to every message on a message waiting line. This key is used to remove a message from a message waiting line, to receive a message, and to reply to a message.

message reference number (MRN)
A unique 16-digit number assigned to each message for identification purposes. The message reference number consists of an 8-digit domain identifier that is followed by an 8-digit sequence number.

Message Repository Manager (MRM)
The name given to the domain and parser associated with messages that are modeled in the workbench.

message-retry
An option available to an MCA that is unable to put a message. The MCA can wait for a predefined amount of time and then try to put the message again.

message routing
A method used for building a logical message and routing it to one or more terminals. The message is scheduled, for each designated terminal, to be delivered as soon as the terminal is available to receive messages, or at a specified time. Terminal operators who receive the message use terminal operator paging commands to view it. A variety of operands on the ROUTE command allow you flexibility when specifying the message destinations.

message segment
One of a number of segments of a message that is too large either for the application or for the queue manager to handle.

message sequence number (MSN)
A sequence number for messages.

message sequence numbering
A programming technique in which messages are given unique numbers during transmission over a communication link. This enables the receiving process to check whether all messages are received, to place them in a queue in the original order, and to discard duplicate messages.

message set
A container for a logical grouping of messages and associated message resources (elements, types, and groups)

message set documentation
A human-readable form of message definitions that is created in the workbench.

message set project
A specialized container for the resources associated with one message set.

message severity
The measurement of how important or significant a message is. The higher the severity level, the more severe or important the condition.

message signal unit (MSU)
An MTP packet containing data.

message store (MS)
A component that is usually associated with the local delivery exit. The message store provides application program interfaces (APIs) for maintaining mailboxes, and it provides pointers to message objects.

message subfile
A subfile where the records are messages from a program message queue.

message switching
The process of receiving a message, storing it, and forwarding it to its destination unaltered.

message template