Device is on and running. It is receiving full power from the system, and is delivering full functionality to the user. Buses in D1 cannot do anything to the bus that would force devices on that bus to lose context. Attains greater power savings than D1. Device is off and not running.
Device context is lost.
Power may be removed from the device. The device driver must restore any device context lost when returning the device to the D0 state. Transitions for the video controller are commanded via the bus-specific control mechanism for device states. Events Display devices incorporating a system power switch should generate a wake event when the switch is pressed while the system is sleeping. A CRT monitor or LCD panel conforming to this specification must support the D0, D2, and D3 states.