Something I had never really thought of before or during the writing of the WsIP were author's notes. But now I'm getting near(er) the end of the first book I guess I should be! Seemingly peculiar to HF the author's note is where you get the chance to separate fact from fiction; justify any controversial choices you've made and point out some extra biographical notes that could not be shoe-horned into the narrative. At least that's what I think they are!
Interestingly some authors don't have them at all - Ken Follett's 'Pillars of the Earth' for example. While others give extensive historical detail and highlight anything they've had to compromise on or change - Bernard Cornwell includes them in each of his novels.
I was of the opinion that less is more; that I could end up writing a new textbook on the WoTR if I'm not careful and they are currently 3 pages long and counting - but that's because I got talking about the Earl of Warwick...again!