switching, in accordance with a request from {HEAD ~ a user} who uses said information related to state of {TAIL ~ degradation}, said information to be displayed to said user to any of said first to third display items 
switching , in accordance with a request from { HEAD ~ a user } who uses said information related to state of { TAIL ~ degradation } , said information to be displayed to said user to any of said first to third display items
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH