With an increase in art theft, the need for positive identification of objects is apparent. The photogrammetric system developed in 1970 is effective in coding an object. The system which is computerized uses a grid laid over photographs of the object. Directions for photography and lighting are given in the article. The information is coded and the objects registered with Interpol. According to the author, objects so marked have not been stolen during robberies in which unregistered objects were taken.