A Monotype keyboard allows a keyboard operator to prepare a punched paper tape, called ribbon, that will direct the casting of type separately from its actual casting.
The keyboard on which the operator types is removable, as is a set of keybars under the keys; the keybars, corresponding to each key, determine which holes will be punched in the tape.
During operation, two sets of keys and keybars are placed in two side-by-side trays on the keyboard.
The keybars are adjustable, so that the coding of the keys can be changed.
Keytops also are replaceable, so that the keyboard can be reconfigured.