A relative positioning system enabling a user to return to {HEAD ~ a starting position} or some other point on {TAIL ~ the users path} 
on
A relative positioning system enabling a user to return to { HEAD ~ a starting position } or some other point on { TAIL ~ the users path }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL