{HEAD ~ The focal plane shutter} is classified into {TAIL ~ two major groups}, i.e., a horizontally running screen type focal plane shutter, and a vertically running blade type focal plane shutter 
is classified into
{ HEAD ~ The focal plane shutter } is classified into { TAIL ~ two major groups } , i.e. , a horizontally running screen type focal plane shutter , and a vertically running blade type focal plane shutter
HEAD HEAD 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 OTH OTH OTH OTH OTH