The combination of the front perimeter edge and the seating axis define {HEAD ~ a front seating area} while {TAIL ~ the combination} of the seating axis and the rear perimeter edge define a rear seating area 
The combination of the front perimeter edge and the seating axis define { HEAD ~ a front seating area } while { TAIL ~ the combination } of the seating axis and the rear perimeter edge define a rear seating area
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH