{HEAD ~ Reference number} 2 in {TAIL ~ parentheses} indicates a second machine frame which is inverted and is intended for grinding the top sides of boards  
in
{ HEAD ~ Reference number } 2 in { TAIL ~ parentheses } indicates a second machine frame which is inverted and is intended for grinding the top sides of boards
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH