elements in the key and in the lock which prevent the lock from changing from the locked condition to the unlocked condition when {HEAD ~ the key} is not connected to {TAIL ~ the lock} and which permit the lock to change from the locked condition to the unlocked condition when the key is connected to the lock, 
is not connected to
elements in the key and in the lock which prevent the lock from changing from the locked condition to the unlocked condition when { HEAD ~ the key } is not connected to { TAIL ~ the lock } and which permit the lock to change from the locked condition to the unlocked condition when the key is connected to the lock ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH