Reference line, 2.5mm long (H bar). This design presents a line of a known size in the field-of-view.
Position of pattern should be specified with respect to the center of the reticle in the notes of the shopping cart during checkout. For example, "Lower left quadrant 8mm from center" or "6mm from center at 9 o'clock position." If nothing is specified, pattern will be centered on the reticle.