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Here is a cool answer to the same question that I posted on YahooAnswers by a cool user with a library background.
The card in the picture was probably used at some point between 1965 and 1978. I think these particular cards were called "needle cards" rather than the regular "index cards" they were based upon. On the other hand, it could perhaps be some kind of "punched card", but I doubt it from the looks of it - they usually have many more holes as they represent a lot of data. I'm not too sure. There might be some information about them on the Internet, but I've had a quick search and couldn't find much, except this short explanation:
The needle card was an index card with prepunched holes near the edges. A category was assigned to each hole position and the appropriate holes were notched out when a card fit a category. To locate all cards that matched a category, a long, thin rod was inserted through the corresponding holes in a tray of cards, the cards were lifted out of the tray, and all of the cards with notched holes dropped out of the stack. The system could also be used to locate all the cards that belonged to two or more categories at once by using more than one needle.