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