Patricia Wrede

Nevertheless, a scene involves characters (who), something happening (what and how), at a particular time (when) and place (where), for some reason (why).

Everything else I can think of has to do with specific subcategories: dialogue scenes, action scenes, contemplative scenes, reaction scenes, emotional scenes, which gets back to complexity and what you want to say and how the scene fits into the story as a whole. And since saying what you want to say is the goal of this whole series, I think that’s a reasonable place to stop.

professional novelist, odds are that sooner or later, you’re going to write an outline