The tub thus has {HEAD ~ sidewalls} defining arm rests, end walls defining a foot rest and back rest, and {TAIL ~ a bottom} defining a seat 
The tub thus has { HEAD ~ sidewalls } defining arm rests , end walls defining a foot rest and back rest , and { TAIL ~ a bottom } defining a seat
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH