Depending on the data format, it might be possible. For example, punch "I" in the first or last column of each card if the first or last column of the card is n

Depending on the data format, it might be possible. For example, punch "I" in the first or last column of each card if the first or last column of the card is not used by the program. Unfortunately, I don't know much about the data formats of punched cards, as I have never used them (except in an emulation of Knuth's MIX system).