The IBM 31 Duplicating Punch or Type 31 Duplicating Punch is an IBM machine that punches numerical and alphabetic data into punched cards. All variants feature both a full alphanumeric keyboard and a separate numeric-only keyboard designed for faster entry of numeric-only card punching. The Type 31 automatically feeds cards from a hopper supporting up to 200 cards and features a duplicating rack, which allows a punched “master card” to automatically reproduce selected columns onto each new card, eliminating repetitive keying. The machine also supports automatic movement between fields using a skip bar, a solid bar mounted above the keyboard that can be adjusted to skip to predetermined columns. ¹