The present invention relates to the design and operation of a frequency selective electrooptic source. The retaining rails are insertable into the guide rails and securable at the guide rails by resilient elements and resilient stops. Pharmaceutical compositions and methods for using them to treat such disorders are provided, as are methods for using such ligands for receptor localization studies: . Therefore, the present invention can reduce the power consumption and allow a multi-level read to be implemented on an actual array with a simple sense amplifier structure step-by-step. Even if the channel quality is lower than predefined at the time of assigning a code word created by channel encoding, the same code word assignment operation as for a transmission portion is performed with respect to a no-transmission portion that a transmitting station does not send to a wireless section.