Computer software (recorded); Computer programs, recorded; Diaphragms (acoustics); Projection screens; Enlarging apparatus (photography); Projection apparatus; Video projectors; Filters for use in photography; Teaching apparatus; Audiovisual teaching apparatus; Electro-dynamic apparatus for the remote control of signals; Remote control apparatus; Slide projectors; Screens (photography); Amplifiers; Objectives (lenses) (optics); Magnifying glasses (optics); Signs, luminous