Portable data storage cartridge encoded multi-position mechanical indicator

An indicator comprises a rotary device in the form of a right cylinder arranged to be rotatable in a chamber of a portable data storage cartridge, which has an exterior wall opening to the chamber. A peripheral surface of the rotary device has an encoded pattern of at least one cylindrical surface and a plurality of facets interrupting the cylindrical surface(s). The facets are located at various axial positions, and at various angularly spaced rotational positions, such that, at differing rotational positions of the rotary device, at least one or none of the facets is positioned at the exterior opening.