A concept in OpenType which allows you to enter spacing adjustments geared to rasterization at particular pixel sizes. If a kerning value that works most of the time leads to an ugly juxtaposition of glyphs on a 12 pixel high font, then you can add a special tweak to the spacing that only is applicable at 12 pixels (and another one at 14 and 18, or whatever is needed). Similar functionality is needed for anchored marks.fontforgeglossary
Print job saved as file which can be printed or displayed on any compatible hardware platform and achieve same results, e.g. PostScript files produce the same results whether printed or shown on a computer monitor.