In the second step, the second, {HEAD ~ outer part} 4 is applied to form {TAIL ~ the actual main cap} 3 
In the second step , the second , { HEAD ~ outer part } 4 is applied to form { TAIL ~ the actual main cap } 3
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH