Some devices can be configured to return a system from sleep when used and this particularly applies to touch devices, especially if the touch screen is the only system interface.
If a device is designed to work in a low power state and able to be used to wake up a system and the associated low level device driver supports wake from sleep then it is possible to use the device to wake up the system.
Currently UPDD only supports this function in Windows. Mac and Linux are to be investigated.
If a UPDD supported touch device is capable of waking up the system then the Device Manager, UPDD Devices, device entry will contain the 'Power Management' tab and the 'Allow this device to wake the computer' will be automatically enabled, as per this example: