{HEAD ~ A retainer} is used for securing the skylight cover over {TAIL ~ the operating leaf frame} 
{ HEAD ~ A retainer } is used for securing the skylight cover over { TAIL ~ the operating leaf frame }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL