3.1.5.3 Heartbeat

If this event occurs while the device is in the ShellRunning state, the device MUST reset the HB timeout timer (section 3.1.2). The device MUST return S_OK if the message is processed successfully. Otherwise, the device MUST return an appropriate error code.

The device MAY have its own native screensaver, of which state is represented by IsNativeScreensaverOn flag. If IsNativeScreensaverOn flag is TRUE and the value of the Screensaver Flag parameter is nonzero, the device MUST suppress the screensaver at the moment by disengaging any active native screensaver. Otherwise, the device MUST let the native screensaver run following the local settings of the device.