In the present invention, control amounts are input from plural sensors. The process according to the present invention aims at avoiding the mandatory implementation of medium-strong to strong acids. Each side plate includes a laterally extending foot with an abutment edge formed or attached thereto a design to limit lateral movement of the upper link over a lower link when the belt is aligned in a helical configuration. In response, display information for displaying the conversations as a list, including first and second rows respectively representing first and second conversations, is sent to the client.