1
general::
Sign in to one's place of business by use of a magnetic card, as in I told him I'd card in for him if he was late tomorrow. Similarly, card out means to sign out of one's place of business, as in I want to sneak out early, so could you please card out for me at the end of the day? This term arose in the 1940s with the invention of automated check-in systems.
American Heritage Idioms