Preferably, one of {HEAD ~ the first and second elements} is fashioned with {TAIL ~ a receptacle}, which receives the other of the first and second elements in the closed condition of the abutment structure, securing the pivoted elements in the closed condition 
is fashioned with
Preferably , one of { HEAD ~ the first and second elements } is fashioned with { TAIL ~ a receptacle } , which receives the other of the first and second elements in the closed condition of the abutment structure , securing the pivoted elements in the closed condition
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH