{HEAD ~ Heterosubstituted hydrocarbyl groups} have {TAIL ~ one or more hydrogen atoms} substituted by a heteroatom, even including one carbon species such as cyano and carboxy 
{ HEAD ~ Heterosubstituted hydrocarbyl groups } have { TAIL ~ one or more hydrogen atoms } substituted by a heteroatom , even including one carbon species such as cyano and carboxy
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH