According to the present invention, a server (100) receives a registration of an itinerary plan including one or a plurality of sets of spot information. Then when one or a plurality of members have been registered in order to allow these members to refer to the itinerary plan, the server (100) sets a reference status for the itinerary plan so that the registered one or plurality of members can refer to the itinerary plan. Then, when a program for causing messages exchanged between the registered one or plurality of members to be chronologically displayed is not running, the server (100) detects whether any editing processes associated with the one or plurality of members have been performed on the itinerary plan. If the server (100) detects that one or more of the editing processes have been performed on the itinerary plan, then when the aforementioned program is later executed to chronologically display messages, the server (100) chronologically displays, in addition to messages exchanged between the one or plurality of members, notification messages each indicating the occurrence or content of one of the one or more editing processes.
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