The arrays of permanent magnets each have north and south poles distributed in {TAIL ~ both longitudinal and latitudinal directions} along {HEAD ~ a plane} 
The arrays of permanent magnets each have north and south poles distributed in { TAIL ~ both longitudinal and latitudinal directions } along { HEAD ~ a plane }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD