An optical wavefront correction plate incorporates a unique, three-dimensional spatial retardation distribution utilizing the index of refraction change of resin mixture in its cured state. New tradable items defined as combinations of other tradable items may be included in the calculation of tradable combinations. When the welding conditions are input, the operating section outputs the conditions to the determining section. In another method, after the first CMP polishing is performed, using a silica slurry containing grains of small particle size which make no aggregation, the second CMP polishing is performed, using a ceria slurry. One or more rogue subscriber stations, included in the respective active subscriber stations, are then identified based on the respective noise and interference levels associated with the respective active subscriber stations. The valve controller 4 is provided with: an operation amount calculation part configured to perform calculation on an inputted value to output a value related to an operation amount for the opening level of the fluid control valve; and a phase compensation part configured to output a value obtained by compensating an inputted value for a phase shift by velocity type digital calculation.