(under subclass 864) Subject matter wherein the agent has a molecular structure which includes a ring or cyclic configuration, which ring contains other than carbon atoms, or wherein the agent is of indefinite molecular weight, greater than 150, and made by reating with each other smaller molecules having definite identities.
(1) Note. The anhydride of a dicarboxylic acid often is a heterocyclic compound, e.g., maleic anhydride, o-phthalic anhydride, etc.
