Abstract: An elongated encoder-strip scale, most typically plastic, is secured to an elongated encoder-strip substrate, most typically metal. The scale has indicia that are at least partially exposed for use in determining the position of a carriage with respect to a chassis in a large-format automatic image-related device--which may be for example a printer, a plotter, or a scanner. The chassis of the image-related device supports an image-bearing sheet, and the carriage scans across the chassis carrying apparatus for forming or sensing marks on the sheet. Preferably the scale is taller than the substrate and mounted to overlap both edges of the substrate, guarding the edges of the substrate. The scale is preferably substantially transparent and mounted for transmission of an optical beam. The substrate is preferably tensioned across the chassis (preferably at a tension under which the scale alone would fail) and threaded, with the scale, through an aperture in the carriage--even during scanning.