{HEAD ~ a fourth switching element} disposed between {TAIL ~ a control terminal} of the first switching element and a control terminal of the third switching element 
disposed between
{ HEAD ~ a fourth switching element } disposed between { TAIL ~ a control terminal } of the first switching element and a control terminal of the third switching element
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH