A router having one or more downstream interfaces and situated in a data network system between sources that send multicast data packets to at least one multicast group address and multiple hosts that request data from the multicast group address and sources. In assaying an antigenic substance in test samples, no use is made of insoluble magnetic particles carrying an antibody specific to the said antigenic substance but insoluble magnetic carrier particles are provided in a state free from adsorbing said antibody, etc. When reading the inspection patterns, the background color is switched, by the use of a background color switching section which faces the sensor with the inspection patterns interposed therebetween and in which a background color is switched. such as but not limited to an SIR estimation module, a power estimation module, a despreading module, a low-pass filter, a combing weight generation module, a coefficient estimation module, a synchronization control channel interference canceller module, etc. In each write drive circuit, the data write current is supplied in response to turning-ON of first and second driver transistors, and the magnetic-field canceling current is supplied in response to turning-ON of the second driver transistor. The charging and billing system has: multiple charging devices that performed charging by supplying electricity; a vending machine, which is separate to the charging devices, and which performs billing according to the amount of electricity supplied during charging; and a transmission line that connects the charging devices to the vending machine so as to enable information to the transmitted.