{HEAD ~ The conductor} can be surrounded by {TAIL ~ additional layers} of polymeric material as long as the outer layer comprises the first polymeric material 
surrounded by
{ HEAD ~ The conductor } can be surrounded by { TAIL ~ additional layers } of polymeric material as long as the outer layer comprises the first polymeric material
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH