M

mailslot

A pseudofile used for one-way interprocess communications.

mailslot client

A process that writes a message to a mailslot.

mailslot server

A process that creates and owns a mailslot and can read messages from it. See also process.

main window

The window that serves as the primary interface between the user and an application.

manual-reset event object

See event object.

mapping

A representation of the elements (or points) from a source coordinate space on a target coordinate space.

mapping mode

An algorithm that specifies the size of the units used for any drawing operations associated with a particular device context.

matrix

An n-dimensional array that is used to specify a transformation. Transformations in a two-dimensional space require either a two-dimensional or a three-dimensional array.

maximize box

A window component that, when clicked, causes the system to enlarge the window to the size of the screen.

maximized window

A window that has the WS_MAXIMIZE style. A maximized top level window fills the screen; a maximized child window fills the client area of its parent window.

maximum tracking size

The largest window size the user can produce by dragging the sizing border.

MCI

See Media Control Interface.

MD4 Message-Digest Algorithm

An algorithm that LSAPI uses in the basic challenge protocol security mechanism. The MD4 Message-Digest Algorithm from RSA Data Security, Inc., uses a message of arbitrary length as input, and returns a 128-bit message digest. See also basic challenge protocol, License Service Application Programming Interface (LSAPI), secret.

MDI client window

See multiple document interface client window.

MDI frame window

See multiple document interface frame window.

Media Control Interface (MCI)

High-level control software that provides a device-independent interface to multimedia devices and media files. MCI includes a command-message interface and a command-string interface.

memory device context (DC)

See compatible device context (DC).

menu

A list of items that represent an application's commands. A menu item can be either a string or a bitmap. See also bitmap, menu item.

menu bar

The topmost menu in a hierarchy of menus. A menu bar typically contains one or more menu items that the user can select to display pop-up menus. See also menu, menu item, pop-up menu.

menu handle

A unique value of the type HMENU used to identify a menu. See also menu.

menu item

A string or bitmap displayed in a menu. Choosing a menu item either sends a command message or activates a pop-up menu. See also bitmap, pop-up menu.

message

A data packet used for communicating information or a request. Messages can be passed between the operating system and an application, different applications, threads within an application, and windows within an application. See also thread, window.

message loop

A program loop that retrieves messages from a thread's message queue and dispatches them to the appropriate window procedures. See also message queue.

message parameters

A pair of 32-bit values that contains information a window procedure uses while processing a message.

message queue

An operating system-defined memory object that holds an ordered list of messages awaiting processing. The system message queue holds mouse and keyboard input waiting to be passed to a thread's message queue. A thread's message queue holds messages waiting to be retrieved by a thread's message loop. See also message loop.

message-type pipe

A named pipe where data is written as a stream of messages. See also named pipe.

metafile

An array of variable-length structures (called metafile records) that store a picture in a device-independent format. A metafile is played when its records are converted to device commands and processed by the appropriate device. (There are two metafile formats: the enhanced format and the Windows format.)

metafile bits

The binary representation of a metafile. The bits include the header, an optional palette, an optional text description of the metafile contents, and the metafile records. See also metafile record, palette.

metafile device context (DC)

A device context that is used for metafile operations. See also device context.

metafile handle table

An array of handles that identify pens, brushes, fonts, and other objects used to create the picture stored in the metafile. See also brush, font, handle, metafile, pen.

metafile header

A structure that specifies the size of the picture stored in the metafile, the size of the metafile (in bytes), the number of entries in the metafile palette, the number of records in the metafile, a pointer to the metafile description (if one exists), and a pointer to the metafile palette (if one exists). See also metafile, metafile palette, palette.

metafile palette

An array of red, green, blue (RGB) values that represent the colors used to create the picture stored in a metafile. See also metafile.

metafile record

A variable-length structure that contains information such as resolution of the device on which the picture was created, the dimension of the picture, and the GDI functions required to create the picture. See also metafile.

Microsoft Locator

A Windows NT® implementation of the Microsoft RPC name-service interface (NSI) for distributed applications. The server application registers its availability, in the form of a name-service entry, with the Locator database. Client applications query the Locator for information such as interface UUIDs, object UUIDs, and network addresses.

MIDI

See Musical Instrument Digital Interface.

MIDI control-change message

A Musical Instrument Digital Interface (MIDI) message sent to a synthesizer to change different synthesizer control settings. An example of a control-change message is the volume controller message, which changes the volume of a specific MIDI channel.

MIDI Manufacturers Association (MMA)

A collective organization composed of Musical Instrument Digital Interface (MIDI) instrument manufacturers and MIDI software companies. The MMA works with the MIDI Standard Committee to maintain the MIDI specification.

MIDI Mapper

Windows systems software that modifies Musical Instrument Digital Interface (MIDI) output messages and redirects them to a MIDI output device using values stored in a MIDI setup map. The MIDI Mapper can change the destination channel and output device for a message, as well as modify program-change messages, volume values, and key values.

MIDI mapping

The process of translating and redirecting Musical Instrument Digital Interface (MIDI) messages according to data defined in a MIDI map setup.

MIDI program-change message

A Musical Instrument Digital Interface (MIDI) message sent to a synthesizer to change the patch on a specific MIDI channel.

MIDI sequence

Musical Instrument Digital Interface (MIDI) data that can be played by a MIDI sequencer.

MIDI sequencer

A program that creates or plays songs stored as Musical Instrument Digital Interface (MIDI) files. When a sequencer plays MIDI files, it sends MIDI data from the file to a MIDI synthesizer, which produces the sounds. Windows provides a MIDI sequencer, accessible through media control interface (MCI), that plays MIDI files. See also Media Control Interface (MCI).

MIDI setup map

A complete set of data for the Musical Instrument Digital Interface (MIDI) Mapper to use when redirecting MIDI messages. Only one setup map can be in effect at a given time, but the user can have several setup maps available and can choose between them by using the MIDI Mapper Control Panel option.

minimize box

A window component that, when clicked, causes the system to reduce the window to the size of an icon.

minimized window

A window that has the WS_MINIMIZE style. A minimized window is the same size as an icon. The system displays a minimized top-level window at the bottom of the screen; the system displays a minimized child window at the bottom of its parent window's client area.

minimum tracking size

The smallest window size the user can produce by dragging the window's sizing border.

MMA

See MIDI Manufacturers Association.

module-definition file

A text file (.DEF) that contains one or more statements describing various attributes of an executable module. A dynamic-link library (DLL) must have a .DEF file to specify the DLL's name and a list of its exported functions. See also dynamic-link library (DLL).

mouse capture

The act of channeling mouse input to a specific window without regard to the position of the mouse-cursor hot spot. See also hot spot, window.

MS-DOS date

A date in the format used by MS-DOS. The date is a packed 16-bit value in which bits in the value represent the day, month, and year.

MS-DOS time

A time in the format used by MS-DOS. The time is a packed 16-bit value in which bits in the value represent the hour, minute, and second.

MSF time format

A time format used by Media Control Interface (MCI) to express time in minutes, seconds, and frames. The number of frames in a second depends on the type of device being used; compact disc audio devices use 75 frames per second. The MSF time format is used primarily by compact disc audio devices.

multibyte character set

A character set in which each character is identified by using more than one byte--for example, a double-byte character set (DBCS). Although Unicode characters are 2 bytes wide, the Unicode character set is not referred to by this term. See also double-byte character set (DBCS), single-byte character set, Unicode.

multiple document interface (MDI) client window

A window that belongs to the MDICLIENT window class. An MDI client window serves as the background for MDI child windows, and it provides support for creating and manipulating child windows. See also window.

multiple document interface (MDI) frame window

The main window of a multiple document interface (MDI) application. See also window.

multiple-selection list box

A list box in which more than one item can be selected at the same time.

Musical Instrument Digital Interface (MIDI)

A standard protocol for communication between musical instruments and computers.

mutex object

An interprocess synchronization object whose state is set to signaled when it is not owned by any thread, and nonsignaled when it is owned. Only one thread at a time can own a mutex. See also nonsignaled, signaled, synchronization object.