{HEAD ~ a casing} having a pump port, {TAIL ~ a tank port}, and an output port, 
{ HEAD ~ a casing } having a pump port , { TAIL ~ a tank port } , and an output port ,
HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH