Method and device for preventing unintended use of print cartridges

In a printer carriage adapted for holding multiple pen cartridges in separate compartments, each carriage compartment includes one or more key-coded barriers at an entrance to the compartment to provide a first level carriage lockout scheme against non-matching cartridge tabs. A second level carriage lockout is provided to differentiate between different families of print cartridges which successfully pass through the first level lockout, which second level is based on predetermined barrier floor configurations in the bottom of each carriage compartment which block non-matching wings on particular print cartridge families.