A card with holes around the edges that can be punched out to code the information on the card for retrieval.
Edge-notched cards have some information written in the body. The holes at the edge are associated with a specific attribute about the subject to be coded for retrieval. A hole is cut out (notched) if the card is to be retrieved for that piece of information. When a thin rod is inserted through the hole associated with an attribute, cards with that hole notched out are not picked up by the rod. Several rods may be inserted to retrieve cards based on more than one attribute.
For example, cards may be created for each member of a group. An individual’s name is written on the card, and possibly other information. Appropriate holes assigned for age and ethnicity are notched. Inserting rods into the holes for a specific age and a specific ethnicity will allow cards that have been notched for both that age and ethnicity to fall out of the cards that are not notched and remain on the rods.