The symbol FC hereinafter stands for fluorocarbon and {TAIL ~ numbers} are chosen for convenience in referring to {HEAD ~ these fluorocarbon compounds} 
The symbol FC hereinafter stands for fluorocarbon and { TAIL ~ numbers } are chosen for convenience in referring to { HEAD ~ these fluorocarbon compounds }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD