TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The photosensitizer component is a metal complex electron-accepting photosensitizer component. The composition has a spectral absorption that is different from the spectral absorption of either the thiosulfate polymer or the metal complex electron-accepting photosensitizing component alone. The sum of the electron-accepting photosensitizer component reduction potential and excitation energy is equal to or greater than the oxidation potential of the thiosulfate group in the thiosulfate polymer. The electron-accepting photosensitizer component is a covalently-connected component of the thiosulfate polymer. The thiosulfate polymer is a copolymer comprising, in random order, (a) 1 mole% of recurring units comprising thiosulfate groups, and (b) recurring units comprising the electron-accepting photosensitizer component, (c) recurring units comprising a pendant charged group, and (d) 1-49 mole% of recurring units having a total neutral charge. The recurring units comprising a pendant charged group are present in an amount of at least 0.1-50 mole%, based on the total recurring units in the copolymer. The recurring units (c) comprise a pendant carboxy, carboxylate, phospho, phosphonate, phosphate, sulfo, sulfonate, or sulfite group. A molar ratio of (a) to (d) is 1:3-3:1. The electron-accepting photosensitizer component is present in an amount of at least 0.1-10 mole%, in relation to the molar amount of thiosulfate groups present in the composition. The electron-accepting photosensitizer component is a compound separate from the thiosulfate polymer. The electron-accepting photosensitizer component is an organic photosensitizer N-containing heterocyclic compound. The electron-accepting photosensitizer component is an inorganic salt or complex. Preferred Composition: The composition further comprises a complexing metal ion, tetraalkyl ammonium ions, an ionomer, and a thiosulfate group as a side chain. The thiosulfate copolymer is capable of undergoing a chemical transformation upon single electron oxidation upon photoexposure, thus causing a change in solubility of the thiosulfate copolymer that is photoexposed. The coating is disposed in a predetermined pattern. EXAMPLE - No suitable example given.