It is so arranged that a user can check whether face detection processing has been set. The control circuit applies a charging voltage to the capacity elements for raising voltage and thereafter applies the discharge voltage from the drive circuit to the discharge electrodes via the capacity elements for raising voltage. As methods of supplying a clock signal to each flip-flop, a plurality of methods different in the adjustable range of clock timing are combined and used. In one arrangement, the mechanism includes a plurality of guide legs having a reduced yield strength in comparison to the mounting legs. With each content data item having the capability of being associated into multiple folders and each folder having the capability of being associated into multiple other folders or file cabinets, the computer system operating the collaboration program gives different users simultaneous, synchronized access to the folders and content data items in the hierarchical structure.