Cards not for Keypunch Use

Part of the Punched Card Collection
by Douglas W. Jones
THE UNIVERSITY OF IOWA Department of Computer Science

SECRET

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If your deck of punched cards contained information critical to the national defense of the United States, you had to protect that information somehow. The solution provided by the government was a "cover sheet" in the form of a card that was to be placed at the head of each such deck of cards. This was in card format, but it was on stock thicker than a card. Therefore, the "cover sheet" had to be removed from the card deck prior to reading the deck, and added back later, after the deck was read.