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