{HEAD ~ The halocarbon refrigerants} used in {TAIL ~ the refrigeration system} described hereinabove are well known in the art 
used in
{ HEAD ~ The halocarbon refrigerants } used in { TAIL ~ the refrigeration system } described hereinabove are well known in the art
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH