{HEAD ~ The opening} 52 is delimited by {TAIL ~ a cylindrical drip ring} or flange 54 
is delimited by
{ HEAD ~ The opening } 52 is delimited by { TAIL ~ a cylindrical drip ring } or flange 54
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH