{HEAD ~ each R17} is independently {TAIL ~ hydrogen}, saturated hydrocarbyl or substituted saturated hydrocarbyl; and 
is independently
{ HEAD ~ each R17 } is independently { TAIL ~ hydrogen } , saturated hydrocarbyl or substituted saturated hydrocarbyl ; and
HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH