{HEAD ~ The current location} of the array may be compared to a reference point to derive at trajectory directing {TAIL ~ the user} to the reference point, such as an originating point 
{ HEAD ~ The current location } of the array may be compared to a reference point to derive at trajectory directing { TAIL ~ the user } to the reference point , such as an originating point
HEAD HEAD 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 OTH OTH OTH OTH OTH OTH OTH