Conveniently, although not necessarily, this will be {TAIL ~ a position} in which {HEAD ~ the reservoir} is at least partially inverted, with the outlet opening thereof in a lowermost position 
in
Conveniently , although not necessarily , this will be { TAIL ~ a position } in which { HEAD ~ the reservoir } is at least partially inverted , with the outlet opening thereof in a lowermost position
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL REL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH