and again... you miss the whole forest for the tree you are staring at.

It has been said time and time again that you need to go over everything in fine detail in order for this to come close to being a design document.

If it encompasses the whole series, then that is what you are writing the DD for... the whole series. You can break it down internally to what is covered each book, but write the thing to cover the whole series.

Get over the fact that you are writing this about a known, hugely popular fiction series. That, my friend, is irrelevant.

What is relevant, is the fact that you do not, as it stands, have anything resembling a design document. People are telling you reasons why it isn't one, and you are still focused on that tree with 'you ain't read the books, so whaddyou know 'bout it?' engraved on it.

Instead of getting defensive about it, think on the things that have been said, incorporate them into your document and make it grow into what you are wanting it to be, instead of leaving it stunted.