Preferably, {HEAD ~ the second step} 46 is positioned adjacent to {TAIL ~ the second end} 18 
is positioned adjacent to
Preferably , { HEAD ~ the second step } 46 is positioned adjacent to { TAIL ~ the second end } 18
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH