{HEAD ~ The stair tread mechanism} is connected with {TAIL ~ a window lock} and initial movement of the stairs unlocks the window 
is connected with
{ HEAD ~ The stair tread mechanism } is connected with { TAIL ~ a window lock } and initial movement of the stairs unlocks the window
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH