The circuit board has {HEAD ~ a groove} in {TAIL ~ a section} of a surface of the circuit board 
The circuit board has { HEAD ~ a groove } in { TAIL ~ a section } of a surface of the circuit board
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH