AFAIK, a dot is standardized by the FAA and/or ICAO (though I don't know the standards/definitions). On a normal display, a dot is a dot, and 2 dots are displayed either side of center for both LOC and G/S. On the 744, the dots are replaced by rectangles on the LOC expanded display, and each rectangle is half a dot (i.e., the display is 4x as sensitive). The 1/3 dot is defined by the diamond cursor first touching a rectangle.