Northern Europe means 'really' Northern Europe. The boundary between AFS routing areas E and L runs along the southern borders of Belgium (EB), Germany (ED/ET) and Poland (EP) and the northern borders of France (LF), Switzerland (LS), Austria (LO) and the Czech Republic/Slovakia (LK).
Flap 5 - not quite correct, the first letter, as I described in my first post, is the AFS routing area, the second is the country. Hence UK, Ireland, Belgium, Netherlands, Luxembourg, Germany, Poland, Denmark, Norway, Sweden and Finland, which are all in routing area E, share the same first letter (E).