About: Edge-notched card
Edge-notched cards or edge-punched cards are a system used to store a small amount of binary or logical data on paper index cards, encoded via the presence or absence of notches in the edges of the cards. The notches allowed efficient sorting and selecting of specific cards matching multiple desired criteria, from a larger number of cards in a paper-based database of information. In the mid-20th century they were sold under names such as Cope-Chat cards, E-Z Sort cards, McBee Keysort, and Indecks cards.
