The IBM/360 column binary format is a standard for representing data as images of Hollerith punch cards. Although punch cards have disappeared, column binary is still widely used in some fields because punch (or bit) coding can be more efficient than dummy coded character formats by a factor as great as 8 to 1 when coding multiple-response data.

A Hollerith card has 80 columns and 12 rows. The rows are labeled, from the top, Y, X, 0, 1-9. The Y punch is sometimes called 12 or V, and the X punch is sometimes called 11. Punches 1-9 and 0 represent the numeric digits, X the minus sign (-) and Y the ampersand (&).

The Hollerith code allowed combinations of punches to represent letters and symbols, but this is rarely used in column binary data today, where punches almost always represent either numbers or response codes.

Modern computers store data in 8-bit bytes, and each column of a card image uses 12 bits, so two bytes are needed to store each column of a card image. The remaining 4 bits out of 16 in each pair of bytes are normally not used in column binary card images, but programs in the QUIP System allow access to these bits by addressing them in column binary modes as punches J, K, L and M.