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