{HEAD ~ means} for securing {TAIL ~ said central portion} to said opening edge of said car body 
for securing
{ HEAD ~ means } for securing { TAIL ~ said central portion } to said opening edge of said car body
HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH