Notifications Specific to Output Devices

Output devices may need to know about external, asynchronous events. In order, each of these events corresponds to accommodate that, pressing a key or button on the following machine. Using these notifications is not appropriate if no physical device exists that is associated with them. OSPM may ignore any of these notifications if, for example the current user does not have permission to change the state of the output device. These notifications are only valid for Output Devices.

Table B-8: Notification Values for Output Devices

Value	Description
0x85	Cycle Brightness. Used to notify OSPM that the output device brightness should be increased by one level. Used to notify OSPM that the user pressed a button or key that is associated with cycling brightness. A useful response by OSPM would be to increase output device brightness by one or more levels. (Levels are defined in _BCL.) If the brightness level is currently at the maximum value, it should be set to the minimum level.
0x86	Increase Brightness. Used to notify OSPM that the output device brightness should be increased by one or more levels as defined by the _BCL object. Used to notify OSPM that the user pressed a button or key that is associated with increasing brightness. If the brightness level is currently at the maximum value, OSPM may should ignore the notification.
0x87	Decrease Brightness. Used to notify OSPM that the output device brightness should be decreased by one or more levels as defined by the _BCL object. Used to notify OSPM that the user pressed a button or key that is associated with decreasing device brightness. If the brightness level is currently at the minimum value, OSPM may should ignore the notification.
0x88	Zero Brightness. Used to notify OSPM that the output device brightness should be zeroed, effectively turning off any lighting that is associated with the device. Used to notify OSPM that the user pressed a button or key associated with zeroing device brightness. This is not to be confused with putting the device in a D3 state. While the brightness may be decreased to zero, the device may still be displaying, using only ambient light.
0x89	Display Device Off. Used to notify OSPM that the device should be put in an off state, one that is not active or visible to the user, usually D3, but possibly D1 or D2. Used to notify OSPM that the user pressed a low power button or key associated with putting the device in an off state. There is no need for a corresponding “device on” notification, for two reasons. First, OSPM may choose to toggle device state when this event is pressed multiple times. Second, OSPM may (and probably will) choose to turn the monitor on whenever the user types on the keyboard, moves the mouse, or otherwise indicates that he or she is attempting to interact with the machine.