Abstract: In a system for displaying prices in a retail store, improved rail arrangements are disclosed to permit improved accuracy in confirming the physical location of an improved display device on one such rail arrangement. A response from the device to a host, or central computer, indicates a particular position of the device on the rail arrangement.

Abstract: A vertical stringer or rail system is provided for use with an electronic price display system in a store, warehouse or other application. A vertical rail is made of an insulating material and is of substantially constant cross section along its extent, with ridges along each edge. A channel in the front face of the rail carries a plurality of exposed conductors, and the channel and edges are keyed. Snap-on connectors fit to the rail, and due to the keying it is impossible to snap the connector on backwards. The snap-on connectors each have a flat cable running to a shelf rail at the front of a shelf, and electronic price display labels lie within the shelf rail. U-shaped snap-on cable clamps provide clamping of the flat cable to the vertical rail nearby to the snap-on connectors, and the cable clamps are captive to the flat cable so they are not easily misplaced. Because the snap-on connectors and clamps may be snapped on at a multitude of locations they can easily accommodate shelves at varying heights.