moving the apparatus and {HEAD ~ user} along {TAIL ~ an indirect path} away from a fixed starting point 
along
moving the apparatus and { HEAD ~ user } along { TAIL ~ an indirect path } away from a fixed starting point
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH