{HEAD ~ Compounds} of {TAIL ~ the formula} ##STR1## the symbols have the meaning described in the specification 
{ HEAD ~ Compounds } of { TAIL ~ the formula } # # STR1 # # the symbols have the meaning described in the specification
HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH