In {TAIL ~ that position}, {HEAD ~ the vent} is located at the interface of the two cells 
In
In { TAIL ~ that position } , { HEAD ~ the vent } is located at the interface of the two cells
REL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH