. "as hydrogen, C1-6 alkyl, C1-6 allyl, C1-6 alkoxy, halogen, maleimide, propargyl ether, glycidyl ether, and the like; and A is a polyvalent linking moiety which can be, for example, aromatic, aliphatic, cycloaliphatic, polycyclic, and heteroatomic." . . . . . .