typedef enum 
{
         PolicyDeviceSystemButton = 0,
         PolicyDeviceThermalZone = 1,
         PolicyDeviceBattery = 2,
         PolicyDeviceMemory = 3,
         PolicyInitiatePowerActionAPI = 4,
         PolicySetPowerStateAPI = 5,
         PolicyImmediateDozeS4 = 6,
         PolicySystemIdle = 7,
         PolicyDeviceMax = 8
} POP_POLICY_DEVICE_TYPE;

Windows Vista Kernel Structures