typedef enum _PLUGPLAY_EVENT_CATEGORY
{
         HardwareProfileChangeEvent = 0,
         TargetDeviceChangeEvent = 1,
         DeviceClassChangeEvent = 2,
         CustomDeviceEvent = 3,
         DeviceInstallEvent = 4,
         DeviceArrivalEvent = 5,
         PowerEvent = 6,
         VetoEvent = 7,
         BlockedDriverEvent = 8,
         InvalidIDEvent = 9,
         PowerSettingChange = 10,
         MaxPlugEventCategory = 11
} PLUGPLAY_EVENT_CATEGORY;

Windows Vista Kernel Structures