However, this is not essential and the three components could each be {TAIL ~ an assembly} of {HEAD ~ parts} 
However , this is not essential and the three components could each be { TAIL ~ an assembly } of { HEAD ~ parts }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD