0-9 A B C D E F G H I J K L M N O P Q R S T U V W XYZ

PREVIOUS PAGE         Return to ANSDIT

(1) A pattern of bits or characters that is used to control the retention or elimination of portions of another such pattern. (2) In computer security, to add data to a transmission to make interpretation of the signal more difficult for an unauthorized user.

In computer graphics, an operation in which regions of an image are set to a constant color value.

The pretense by an entity to be a different entity in order to gain unauthorized access.

Massachusetts General Hospital Utility Multiprogramming System:

massively parallel processing (MPP):
Processing of data structures by means of simultaneous execution of hardware operations on multiple processors with dedicated memories. MPP is typically organized as multidimensional arrays and may be used for such applications as Fast Fourier Transforms and artificial neural networks.

master clock:
A clock whose main function is to control the pulse repetition rate of other clocks.

master key:
In computer security, the top-level key in a hierarchy of key-encrypting keys.

master station:
In basic mode link control, the data station that has accepted an invitation to ensure a data transfer to one or more other stations. At a given instant, there can be only one master station on a data link.

master task:
A module of a program whose execution creates a task.

A comparison that is made to determine similarities or differences of the items compared. Contrast with hit.

material requirements planning (MRP):
A priority planning technique which is driven by a master production schedule (MPS) and which relates component demands to the production schedules for parent items.

mathematical check:
A programmed check that is based on mathematical relationships. Synonymous with arithmetic check.

mathematical induction:
A method of proving a statement concerning terms based on natural numbers not less than N by showing that the statement is valid for the term based on N and that, if it is valid for an arbitrary value of n that is greater than N, it is also valid for the term based on (n+1).

mathematical logic:
Synonym for symbolic logic.

mathematical model:
A mathematical representation of a process, device, or concept.

mathematical morphology:
An image algebra whose variables are shapes and whose operations transform those shapes. Synonymous with morphology.

(1) A rectangular arrangement of elements, arranged in rows and columns, that may be manipulated according to the rules of matrix algebra. (2) By extension, an arrangement of any number of dimensions. (3) In computers, a logic network in the form of an arrangement of input leads and output leads with gates connected at some of their intersections.

matrix array sensor:
Synonym for area array sensor.

matrix printer:
Synonym for dot matrix printer.

matrix storage:
Storage whose elements are arranged in such a manner that access to any location requires the use of two or more coordinates; for example, cathode ray storage.

medium attachment unit.

maximize :
To replace an icon with a window. Contrast with to iconize.

Microchannel Architecture.

management domain.

manipulation detection code.

medium-dependent interface.

mean down time.

mean access time:
The average access time resulting from the normal operation of a device.

mean conditional information content:
Synonym for conditional entropy.

mean down time (MDT):
For a given functional unit, the average value of down time under stated conditions. The stated conditions may be used to segregate down times such as time to repair, time to recover, time to perform preventive maintenance, etc.

mean information content:
Synonym for entropy.

means-end analysis:
A problem solving technique that, at every step, searches for operators that maximally lower the difference between the existing state and a known goal state.

mean time between failures (MTBF):
For a given functional unit, under stated conditions, the average duration between consecutive failures. Mean time between failures can be derived from a theoretical model or from observations.

mean time to failure (MTTF):
For a given functional unit, under stated conditions, the average duration from the instant it is first put into use or is put to use after restoration until a failure occurs. Mean time to failure can be derived from a theoretical model or from observations.

mean time to recovery:
For a given functional unit, the average duration required for restoration of operations after a failure. Synonymous with mean time to restoration.

mean time to repair (MTTR):
(1) For a given functional unit, under stated conditions, the average duration required for corrective maintenance. (2) Deprecated synonym for mean time to recovery.

mean time to restoration:
Synonym for mean time to recovery.

mean transinformation content:
The mean value of the transinformation content of two events, each in one of two finite sets of mutually exclusive and jointly exhaustive events; in mathematical notation, this measure is:
T(X, Y)   =
p(xi, yj) T(xi, yj)

where: X={x1...xn} is the set of events xi (i = 1 ...n), Y={y1 ...ym} is the set of events yj (j = 1 ...m), T(xi,yj) is the transinformation content of xi and yj, and p(xi,yj) the joint probability that both events occur. The mean transinformation content is symmetric in X and Y. It is also equal to the difference between the entropy of one of the two sets of events and the conditional entropy of this set relative to the other:

T(X,Y) = H(X) - H(X|Y) = H(Y) - H(Y|X) = T(Y,X).
The mean transinformation content is a quantitative measure of information transmitted through a channel, when X is a specific set of messages at the message source and Y is a specific set of messages at the message sink. It is equal to the difference between the entropy at the message source and the equivocation, or the difference between the entropy at the message sink and the irrelevance. Synonymous with average transinformation content.

mechanical mouse:
A mouse whose movement is converted into signals by interpreting the movement of a wheel-and-bushing system.

median filtering:
Local transformation in which each pixel value is replaced with the median of the pixel values of the neighbor pixels. Median filtering is used for smoothing.

(1) The means through which data are acquired, perceived, represented, displayed, stored, or transmitted. (2) The means through, in, or on which data are preceived, represented, displayed, stored, or transmitted.

medium access control (MAC):
A technique used to establish the sequence of data stations that are in temporary control of the transmission medium.

medium access control protocol:
In a local area network, the protocol that governs access to the transmission medium, taking into account the topological aspects of the network, to enable the exchange of data between data stations. (Figure 39 - Example of a protocol structure for a LAN).

medium access control sublayer:
In a local area network, the part of the data link layer that applies medium access control and supports topology-dependent functions. The MAC sublayer uses the services of the physical layer to provide services to the logical link control sublayer. (Figure 39 - Example of a protocol structure for a LAN).

medium attachment unit (MAU):
In a data station on a local area network, a device used to couple the data terminal equipment to the transmission medium. (Figure 39 - Example of a protocol structure for a LAN).

medium-dependent interface (MDI):
At a data station on a local area network, the mechanical and electrical interface between the transmission medium and a medium attachment unit. (Figure 39 - Example of a protocol structure for a LAN).

medium interface connector (MIC):
In a local area network, the connector used to attach a data station to a trunk coupling unit, trunk cable, or drop cable. (Figure 3 - Interconnection of data stations on a trunk cable). (Figure 39 - Example of a protocol structure for a LAN).

Synonym for MFLOPS.

member recipient:
A potential recipient to which a message is conveyed as a result of distribution list expansion.

member record:
In a network model for databases, a record which is subordinate to the owner record in a set.

(1) Any of the addressable storage space in a processing unit or any other internal storage that is used to execute instructions. (2) All of the addressable space in internal storage. (3) Loosely, synonymous with main storage, however, in calculators, microcomputers, and some minicomputers, the term "memory" is preferred to the term "main storage".

memory address register (MAR):
A register in a processing unit that contains the address of the storage location being accessed.

memory card:
Deprecated synonym for flash memory card.

memory cartridge:
A RAM cartridge typically used in portable computers to store data.

memory dump:
A dump of the contents of all or part of the internal storage of a computer. Usually in binary, octal, or hexadecimal form.

memory management unit (MMU):
A functional unit that provides protection, sharing, and allocation of memory blocks. The memory management unit may support virtual memory and paging by translating virtual addresses into real addresses, and may be responsible for address multiplexing and the refresh cycle of dynamic RAM.

memory protection:
An arrangement for restricting access to various parts of memory to programs for which access has been authorized.

A list of options displayed by a data processing system, from which the user can select an action to be initiated.

menu bar:
An area usually along one edge of a window used to display names or icons for menus. Synonymous with action bar.

To combine the items of two or more sets of data that are in the same given order into one set in that order.

merge sort:
A sort program in which the elements in a set are divided into subsets, the items in each subset are sorted, and the resulting sorted subsets are merged. For large files, this process may be carried out iteratively.

mesh network:
A network in which there are at least two nodes with two or more paths between them. (Figure 43 - Network topologies).

(1) A quantity of data that is complete in some sense and that has been transferred, or has been structured for such transfer, from one entity to another for interpretation and action. (2) In information theory and communication theory, a sequence of characters intended to convey information. (3) In programming languages, a request for an object to perform one of its operations. (4) In electronic mail, an information object transferred between user agents. A message usually consists of two parts: content and header.

message authentication:
Verification that a message was sent by the purported originator to the intended recipient and that the message was not changed in transit.

message authentication code:
In computer security, a bit string that is a function of both data (either plaintext or ciphertext) and a secret key, and that is attached to the data in order to allow data authentication. The function used to generate the message authentication code must be a one-way function.

message handling:
A distributed information processing task that integrates the intrinsically related subtasks of message transfer and message storage.

message handling environment (MHE):
The environment that includes the message handling system, users, and distribution lists.

message handling service:
(1) An application service element that provides a generalized facility for exchanging electronic messages between systems. Synonymous with message-oriented text interchange system. (2) Service provided by a message handling system.

message handling system (MHS):
An organized set of functional units that can convey messages from one correspondent to another.

message identification service:
A service that enables the message transfer system to provide a user agent with a unique identification for each message or probe submitted to or delivered by the system, for example: a time stamp.

message-oriented text interchange system (MOTIS):
Synonym for message handling service.

message retrieval:
The process of obtaining incoming messages from a mailbox.

message sink:
That part of a communication system in which messages are considered to be received.

message source:
That part of a communication system from which messages are considered to originate.

message storage:
In electronic mail, the automatic storage of messages for later usage within the message handling system.

message store (MS):
The functional unit that provides a single direct user with capabilities for message storage.

message switching:
In a data network, the process of routing messages by receiving, storing as necessary, and forwarding complete messages. Contrast with circuit switching, packet switching.

message transfer (MT):
In electronic mail, the conveyance of messages using computer networks.

message transfer agent (MTA):
A functional unit of the message transfer system that conveys messages to users or to groups of users identified by distribution lists.

message transfer system (MTS):
A functional unit consisting of one or more message transfer agents that provides store-and-forward message transfer between user agents, message stores, and access units.

messaging subsystem:
A part of a message handling system with functional significance, for example: a user agent, mail exploder.

messaging system:
A data processing system used in the implementation of a message handling system.

Synonym for compiler generator.

Data about data, including their data descriptions, ownership, access paths, access rights, and data volatility.

Knowledge about the use and control of domain knowledge.

A language used to specify some or all aspects of another language and possibly itself; for example, Backus-Naur form.

Meta Object Facility (MOF):
A language in which metamodels can be described and that serves as a general-purpose standard for high-abstraction modeling.

A rule that prescribes the conditions, sequence, and manner in which another rule or a given set of rules should apply.

metastable state:
Synonym for quasistable state.

In programming languages, a procedure or set of actions that an object executes upon receipt of a message.

metropolitan area network (MAN):
A network that provides communication services to a geographical area larger than a local area networks but restricted to a single urban area.

A unit of measurement of processing performance equal to one million floating-point operations per second. This unit of measurement is used in scientific computer applications. Synonymous with megaflops. MFLOPS is the abbreviation for million floating-point operations per second.

MFM recording:
Synonym for modified frequency modulation recording.

message handling environment.

A standardized method of structuring hypermedia and multimedia data. MHEG is derived from Multimedia and Hypermedia Information Coding Expert Group.

message handling system.

Next Page