{HEAD ~ The typical prior art atmosphere vent} 16 is replaced by {TAIL ~ the expanded vent} 18 in the present invention 
is replaced by
{ HEAD ~ The typical prior art atmosphere vent } 16 is replaced by { TAIL ~ the expanded vent } 18 in the present invention
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH