There's always the character list, with name and any significant details, so that when Princess Esmeralda returns to court, I don't have to remember the name of the spiteful gossip there, thirteen chapters earlier.
And there are others. Location lists for the well-traveled. Lists of types of Good Folk. Whatever.
For my NaNoWriMo novel, it's points of view.
Multi-point-of-view can range from a main character and other points of view only to look at him, to the ensemble production that I am trying. In the latter, you need to juggle some equality. Having made arbitrary decisions last night, I concluded I needed a list, to discover who's seeing too much and who too little.
Ariana for the first. And Theo for the last. Crystal clear as soon as I made the list. Cedric and Susan are perhaps all right, but Dora and Tam and Loveday could do more. Except of course the increase of one is the decrease of another.
Juggle, juggle, juggle. . . . . sigh.