It can also use fonts which map glyphs via characters which do not represent the final visual item e.g. "PDF" could be "1#F" and you only really know what it lo

It can also use fonts which map glyphs via characters which do not represent the final visual item e.g. "PDF" could be "1#F" and you only really know what it looks like by rendering then viewing/OCR. A nice file won't, but sometimes the best work is in not dealing with nice things.