Aperture card
A punched card with a cut-out window holding a chip of 35 mm microfilm — the card indexes, the film carries the image.
The aperture card solved a filing problem: how do you store an A0 drawing so a machine can find it? You cut a window in an ordinary 80-column punched card and mounted a frame of 35 mm film carrying a single document image, usually an engineering drawing. The punches in the card held the metadata — drawing number, revision — so the same card sorters that handled everyday data processing could sort and retrieve the right drawing.
Engineering departments, the military and the aerospace industry leaned on aperture cards from the 1950s well into the 1990s, before scanned files took over. One card, one drawing, searchable without a computer.