{HEAD ~ Use} of {TAIL ~ three rails} makes a total length of the slide rail shorter to provide a compact slide rail 
of
{ HEAD ~ Use } of { TAIL ~ three rails } makes a total length of the slide rail shorter to provide a compact slide rail
HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH