NAME
	Flush -- clear all queued I/O requests for the parallel port

   FUNCTION
	This command purges the read and write request queues for the
	parallel device. The currently active request is not purged.

   IO REQUEST
	io_Message      mn_ReplyPort initialized
	io_Device       set by OpenDevice
	io_Unit         set by OpenDevice
	io_Command      CMD_FLUSH (08)