{HEAD ~ The lower portion} is recessed relative to the upper portion in {TAIL ~ a direction} toward the opposite cutting edge 
{ HEAD ~ The lower portion } is recessed relative to the upper portion in { TAIL ~ a direction } toward the opposite cutting edge
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH