Hi - ok I will scratch around again. I'm surprised nobody has documented this with a full explanation on a static web page. Most of the posts here are incomplete and so are the blogs I've found off this site. It would be a shame for this data to remain unseen by many who might use it to make further inroads into the kindle, given all the good work you and others have put in.
Please don't take this as a snipe because as I say the work done is great and also your code is well documented.