{HEAD ~ The frame} is constructed including {TAIL ~ a base frame} and an operating leaf frame usually referred to as an operating leaf frame or operating leaf 
is constructed including
{ HEAD ~ The frame } is constructed including { TAIL ~ a base frame } and an operating leaf frame usually referred to as an operating leaf frame or operating leaf
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH