Have a question about how the TVTropes wiki works? No one knows this community better than the people in it, so ask away! Ask the Tropers is the page you come to when you have a question burning in your brain and the support pages didn't help.
It's not for everything, though. For a list of all the resources for your questions, click here. You can also go to this Directory thread
for ongoing cleanup projects.
The difference is that All There in the Manual is about an outside Word of God source clarifying In-Universe stuff, which makes it easier to trope the content sof said manual. For example, say that a show has a character that is The Ghost (mentioned but not seen in the work himself) but the Manual has revealed him to be a Wholesome Crossdresser White Haired Preety Boy with a Ring of Power and Girlish Pigtails. If ATITM becomes a trivia trope, then would the character in question still count for the other tropes, or will thye be moved to the Trivia tab as well?
If the latter, then what will happen to other examples of these tropes that are showcased in the work itself?
The vast majority of people who experience the work will not seek out any expanded material that may be associated with it, such as the book, the liner notes, interviews with the writer, etc. The purpose of All There in the Manual is to call out the content that is only found in such material; it is as much Trivia as Word of God.
If a trope is found only in that external material, then it is not a trope present in the work. That is my opinion.
"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"Fighteer is correct. Anything in material outside of the work is not a trope in the work. The "manual" is NOT part of the work. Therefore All There in the Manual should be trivia.

Per several posts I've seen here and elsewhere, TV Tropes' definition of trivia includes "anything outside of what you see in the work itself." (If I am wrong feel free to correct me.)
That being said, since All There in the Manual is outside of the work shouldn't it be Trivia and get a Trivia banner?