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Edge-notched card

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Keysort cards used in World War II codebreaking

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.[1] 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 cards,[2] and Indecks cards.[3] They are also informally called needle cards since they can be sorted with long knitting needles.


Edge-notched card used as a library card. Edges not notched here.
A notched card showing two levels of notching.
Hand tool for notching cards.

Edge-notched cards are a manual data storage and manipulation technology used for specialized data storage and cataloging applications through much of the 20th century. An early instance of something like this methodology appeared in 1904.[4] While there were many variants, by the mid-20th century a popular version consisted of 5-by-8-inch (13 by 20 cm) paperboard cards with holes punched at regular intervals along all four edges, a short distance in from the edges. The center of the card might be blank space for information to be written, or contain a pre-printed form, or contain a microform image in the case of edge-notched aperture cards.[5][6]

To record data, the paper stock between a hole and the nearest edge was removed by a special notching tool. The holes were assigned a meaning dependent upon a particular application. For example, one hole might record the answer to a yes/no question on a survey, with the presence of a notch meaning "yes". More-complex data was encoded using a variety of schemes, often using a superimposed code which allows more distinct categories to be coded than the number of holes available.

To allow a visual check that all cards in a deck were oriented the same way, one corner of each card was beveled, much like Hollerith punched cards. Edge-notched cards, however, were not intended to be read by machines such as IBM card sorters. Instead, they were manipulated by passing one or more slim needles through selected holes in a group of cards. As the needles were lifted, the cards that were notched in the hole positions where the needles were inserted would be left behind as rest of the deck was lifted by the needles. Using two or more needles produced a logical and function. Combining the cards from two different selections produced a logical or. Quite complex manipulations, including sorting were possible using these techniques.[7]


Before the widespread use of computers, some public libraries used a system of small edge-notched cards in paper pockets in the back of library books to keep track of them.[8][9] Edge-notched cards were used for course scheduling in some high schools and colleges during the same era.[10]

The corporate library of a division of E. I. du Pont de Nemours and Company maintained a subject catalog on two-level edge-punched cards (Royal-McBee Keysort cards) that grew to 15,000 cards before the librarians began to consider keeping the catalog on a computer.[11]

See also[edit]


  1. ^ Casey 1958.
  2. ^ Casey 1958, p. v.
  3. ^ Kelly 2008.
  4. ^ Casey 1958, p. 4.
  5. ^ Ellsworth 1951.
  6. ^ Cady 1999, p. 182.
  7. ^ For example: Robert S. Casey & James W. Perry, "Elementary manipulations of hand-sorted punched cards", in Casey 1958, pp. 12–29.
  8. ^ Kilgour 1939.
  9. ^ "An old library book card". plakboek.livejournal.com. Retrieved 2011-03-29. An example of an edge-notched library card.
  10. ^ Anderson & Van Dyke 1963.
  11. ^ Grandine, Starr & Putscher 1961.