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