Abstract: An edible product such as a unit dosage form of a pharmaceutically active substance includes a layer of a material that can receive and retain a high resolution microrelief that can convey information. The microrelief is themo-formable, preferably formed from an aqueous solution of HPMC and/or HPC plus a plasticizer and colorant. Other additives such as strengtheners, surfactants and adherents may be used depending on the application. The materials are selected and proportioned to control the fading or change in color of the visual image or effect produced by the relief to indicate exposure to an unacceptable degree of heat or humidity. The dosage form can be the relief-containing layer itself with the pharmaceutical carried therein. In a preferred form, the layer is an outer coating over a core containing the pharmaceutically active substance. Coated tablets are configured to resist twinning.