The invention provides small-sized, power-saving and easily-producible magneto-optical devices. A distinguishing factor associated with a given data stream may be determined and used as a basis for selecting a QoS policy setting for the given data stream. On the other hand, when a touch-down operation is detected in an area of the second item while the second item is selected, the display control apparatus validates a move operation for selecting other items. The acoustic coupler carries acoustic signals in the 1-200 MHz frequency range between the acoustic transducer and the contacted section of the surface of the object.