Patent classifications
G
PHYSICS
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G06
COMPUTING OR CALCULATING; COUNTING
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G06K
GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
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21/00
Information retrieval from punched cards designed for manual use or handling by machine; Apparatus for handling such cards, e.g. marking or correcting
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G06K21/02
in which coincidence of markings is sensed mechanically, e.g. by needle
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