UFO and glyphOrder

After using Glyphs to convert a .vfb file to UFO, the lib.plist file contains both com.schriftgestaltung.glyphOrder and public.glyphOrder keys with nearly identical content – the only difference is public.glyphOrder includes .notdef though, interestingly, it is at the end of the list rather than at the beginning where I would have expected it. So, lots of questions:

  1. Why is .notdef at the end of public.glyphOrder rather than the beginning?
  2. Why is .notdef absent from com.schriftgestaltung.glyphOrder ?
  3. How should we view these two glyphOrder lists:
    – when does Glyphs use which?
    – What if one or the other is absent, what changes?
    – If both are present but different, which is used?