After reaching the last ordered path, the first node of {HEAD ~ each path} in {TAIL ~ the group} is removed 
in
After reaching the last ordered path , the first node of { HEAD ~ each path } in { TAIL ~ the group } is removed
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH