a) a door mounted on a frame for {HEAD ~ lateral movement} on {TAIL ~ tracks} between a first open position and a second closed position 
on
a ) a door mounted on a frame for { HEAD ~ lateral movement } on { TAIL ~ tracks } between a first open position and a second closed position
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH