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