A complete roll of {HEAD ~ wrapping material} comprises several wrapping portions, which are held and released at {TAIL ~ their lateral ends} 
A complete roll of { HEAD ~ wrapping material } comprises several wrapping portions , which are held and released at { TAIL ~ their lateral ends }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL