An improved method for instructing how to most efficiently effect a product changeover on an assembly line includes the steps of providing an instructional animation which schematically shows the steps which are to be taken by a plurality of workers to effect the changeover. The personal computer PC1 authenticates a memory card MC as genuine under management of the system administrator. For this purpose, respectively associated interferometry and Moir\xe9 structures can be introduced on the object side and image side.