At a second position, in which {HEAD ~ the stem} is withdrawn by {TAIL ~ one step} from the most inserted first position, the stem is allowed to turn in both the right and left directions by a suitable angle 
is withdrawn by
At a second position , in which { HEAD ~ the stem } is withdrawn by { TAIL ~ one step } from the most inserted first position , the stem is allowed to turn in both the right and left directions by a suitable angle
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH