{HEAD ~ A helicopter} above the tree is connected to {TAIL ~ a point} near the top of the trunk 
is connected to
{ HEAD ~ A helicopter } above the tree is connected to { TAIL ~ a point } near the top of the trunk
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH