{HEAD ~ a stiffener} defining {TAIL ~ an opening} in a central portion thereof and having front and rear ends, the stiffener having an locking hook close to the front end along a first side of the stiffener 
defining
{ HEAD ~ a stiffener } defining { TAIL ~ an opening } in a central portion thereof and having front and rear ends , the stiffener having an locking hook close to the front end along a first side of the stiffener
HEAD HEAD HEAD HEAD HEAD HEAD 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 OTH OTH OTH OTH OTH OTH