B

background window

Any window created by a thread other than the foreground thread.

base character

A character followed by a nonspacing character; typically, this is a letter that receives an accent mark. For example, in the character è, an accented e, the e is the base character. See also nonspacing character.

base class

The window class an application uses as the starting point when creating a superclass. See also superclass.

base line

An imaginary line where the capital letters for a given font rest. See also font.

base priority

A thread priority value that provides the basis for calculating the thread's dynamic priority. This value is set to one of the five levels within the priority class of the thread's process. The scheduler can temporarily boost the priority of a thread, but it cannot reduce it below this base. See also dynamic priority, priority class, process, thread.

basic challenge protocol

A security mechanism that all LSAPI-compliant license systems support. It requires independent maintenance of a minimum of four secret values by both the licensed application and the license server, and mutual authentication of one value before the license server grants licensing resources. See also License Service Application Programming Interface (LSAPI), MD4 Message-Digest Algorithm, secret.

beginning-of-medium marker

The position on a tape where you can begin recording data.

beginning-of-partition marker

The position in a partition where you can begin recording data. If there is only one partition, this position is usually equivalent to the beginning-of-medium marker.

Bezier spline

An irregular curve defined by four points: two endpoints and two control points. The endpoints determine where the curve begins and ends. The control points determine the shape of the curve; however, unlike the endpoints, the control points do not intersect the curve.

bit count

The number of bits of data in a color plane that represent a single pixel. See also pixel.

bitmap

An array of bits that contains data that describes the colors found in a rectangular region on the screen (or the rectangular region found on a page of printer paper). See also rectangular region.

bitmapped image

A rectangular image on a video display (or page of printer paper) represented by the color data in a bitmap.

blink time

The elapsed time, in milliseconds, required to invert the caret display. This value is half of the flash time. See also caret, flash time.

blocking input and output (I/O)

A wait mode for I/O operations on a named pipe where functions wait for a process on the other end of the pipe to perform an action. In nonblocking wait mode, the functions return if their operations are not finished immediately. See also named pipe, pipe, process.

bottom-up DIB

A device-independent bitmap (DIB) whose origin lies at the bottom-left corner. See also top-down DIB.

bounding rectangle

A Windows or graphics device interface (GDI) object. In the case of some GDI objects, the dimensions of this rectangle are inclusive-exclusive when no world transformation has been set, and inclusive-inclusive when a world transformation has been set.

break key

In Media Control Interface (MCI), a keystroke that interrupts a wait operation. By default, MCI defines this key as ^CTRL+BREAK^. An application can redefine this key by using the MCI_BREAK command message.

breakpoint

A location in a process where execution is stopped to allow the developer to examine the process's code, variables, and register values, and, as necessary, make changes, continue execution, or terminate execution.

brush

A bitmap that is used to fill the interior of closed shapes, polygons, ellipses, and paths. See also bitmap, ellipse, path, polygon.

brush origin

A coordinate that specifies the location of one of the pixels in a brush's bitmap. Windows maps this pixel to the upper left corner of the window that contains the object to be painted. See also bitmap, pixel, window.

button

An element in the Windows user interface that enables a user to provide input to an application. Buttons are typically used in dialog boxes.

byte-order mark

A special Unicode character (0xFEFF) that is placed at the beginning of Unicode text files to indicate that the text is in Unicode format.

byte reversed

A Unicode file in which the most significant byte is first (as on Motorola architectures).

byte type pipe

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