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