{HEAD ~ These data} requiring {TAIL ~ storage} are stored in a storage device installed in the optical network unit 
{ HEAD ~ These data } requiring { TAIL ~ storage } are stored in a storage device installed in the optical network unit
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH