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