| 摘要 |
A data processing card is provided with one or more apertures each with a window rotatably mounted with respect thereto. The window may be of polarizing material or bear an indicating arrow or the like. Information is set into the card by rotating each window to selected angle conveniently done with a pencil applied to a tab attached to the window and registerable with indexing marks on the card. Two or more cards can be superimposed one upon the other with their apertures aligned. By illuminating the stack of cards from the rear, the information on the several cards can be examined from the front for matching and mismatching of information. If a bit of information on one card corresponds with the bit of information on the other card in a corresponding window, their polarizing filters will be oriented in the same manner and light will pass. If the information bits are different, the filters will be differently oriented and light will be blocked.
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