You use the device IOCTL interface in an application to carry out "low-level" operations that are not supported by the Win32 API and that require direct communication with a VxD. Windows 95 implements the interface through the DeviceIoControl function, which sends commands and accompanying data directly to the given VxD. To use the interface, you open the VxD by using the CreateFile function, send commands to the VxD by using DeviceIoControl, and finally close the VxD by using the CloseHandle function.