Reserved IOCTL codes
All the following IOCTL codes are reserved, unless explicitly defined above; the driver MUST return STATUS_INVALID_DEVICE_STATE from any of the following:
CTL_CODE(FILE_DEVICE_NFP, 0x0000, *, *) through CTL_CODE(FILE_DEVICE_NFP, 0x00FF, *, *)
The following IOCTLs MAY be used for IHV-specific functionality:
CTL_CODE(FILE_DEVICE_NFP, 0x0100, *, *) through CTL_CODE(FILE_DEVICE_NFP, 0x01FF, *, *)