{HEAD ~ The connector part} 17 consists of {TAIL ~ projecting tabs} 18, which taper to a point at their free ends 
consists of
{ HEAD ~ The connector part } 17 consists of { TAIL ~ projecting tabs } 18 , which taper to a point at their free ends
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH