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