V

value

Data associated with a key. A key may have zero or more values. Each value has three parts: a name, a type, and data. See also key.

vector device

A device that creates text and graphics output by drawing lines.

viewport

A rectangle in device space that is used to specify a transformation between page and device space. The viewport extents are always measured in pixels for a video display or dots for printers.

viewport extent

The width or height of the viewport.

viewport origin

The corner of the viewport from which the extents are measured. (The viewport-origin coordinates are specified with respect to the device-space origin.)

virtual-key code

A device-independent value that identifies the purpose of a keystroke as interpreted by the Windows keyboard device driver.

visible region

The part of the client area that is visible to the user.

visible window

A window that has the WS_VISIBLE style. A visible window is displayed on the screen and can receive user input.

volatile key

A key that is valid only until the next time the operating system is started. See also key.

volume

A storage medium, such as a disk or tape, that is formatted to contain files and directories. A volume is accessed through a disk drive. In a path, a volume is referenced by the letter of the disk drive that accesses the volume. For example, a fixed disk may be referred to as C. A single volume may be divided into more than one logical volume, also called a partition. Each partition is referenced by a unique volume identifier.

volume scalar

A component of a Musical Instrument Digital Interface (MIDI) Mapper patch map that adjusts the volume of a patch on a synthesizer. For example, if the bass patch on a synthesizer is too loud relative to the piano patch, the volume scalar can reduce the volume for the bass or increase the volume for the piano. (Applications playing waveform audio can also adjust the output volume.) See also MIDI Mapper, patch.