A method for retrieving based on a search term together with its corresponding meaning from a set of base documents those documents which contain the search term and in which the certain search term has the certain meaning to enable the building of an index on the retrieved documents. The aperture restricts light incident on the photodetector from a predetermined portion of the sample surface. As a result, a vehicle speed according to the depression amount of the traveling accelerator pedal is obtained even when the internal combustion engine rotates at high speed. The OAE is inserted into the beam path and adjusted. By using means external to the vessel to rotate andor stabilize the magnetic bearing levitating in the fluid, including possibly rotating the superconducting element itself or moving it relative to the vessel, the desired effective pumping or mixing action may be provided. The first electrode and the second electrode are formed in a region in a layer different from a layer of the analog switch, the region extending over the analog switch.