The wall limits vertical movement of a hook connected to {HEAD ~ the hook anchor} to prevent {TAIL ~ inadvertent disengagement} by vertical movement 
The wall limits vertical movement of a hook connected to { HEAD ~ the hook anchor } to prevent { TAIL ~ inadvertent disengagement } by vertical movement
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH