{HEAD ~ R9} is {TAIL ~ hydrogen}, alkyl of 1 6 carbon atoms, or aralkyl of 7 10 carbon atoms 
{ HEAD ~ R9 } is { TAIL ~ hydrogen } , alkyl of 1 6 carbon atoms , or aralkyl of 7 10 carbon atoms
HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH