{HEAD ~ A tensioning drive} is provided at {TAIL ~ one end} of a section of the predetermined course 
{ HEAD ~ A tensioning drive } is provided at { TAIL ~ one end } of a section of the predetermined course
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH