A cue point data structure is maintained independent of a recorded time-varying content file. In order to achieve the highest possible propulsion in the water with the lowest possible use of force, the power transfer element is mainly designed flow dynamically, in cross section in the X-Z level with a longer Z axis and short X-axis. If so, a protection action is performed on the service access information, on an entire service message or to one or more portions thereof, for example, to protect the sensitive information. An operating current of the differential amplifying MOSFET is increased through the use of a current flowing in the capacitor due to such an external power variation, thereby executing the operation of stabilizing an output voltage corresponding to the reduction in the external power supply voltage.