A locking system enabling selectively handed handle turning as for unlocking a door, comprising in combination, drive means including said handle rotatable clockwise and counterclockwise, driven means including a part movable linearly in a primary direction, to operate door lock structure, and coupling means including a handle rotation direction selector having first and second alternate positions, and operable to displace said part in said primary direction in response to handle clockwise rotation when the selector is in first position, and alternatively to displace said part in said primary direction in response to handle counterclockwise rotation when the selector is in second position, as for example in relation to two parallel racks.