Category Types
Found at Admin → Category Types, only shown for programs that have this feature turned on, since not every program needs it.
A category type is a label you group categories under, for example "Event" categories vs "Achievement" categories, if your program has both. The point of grouping is the AI Rules page: entry-text and citation-writing rules can be set once per category type instead of once per category, and once per program if all your categories share the same style. Create a type at Admin → Category Types → + New Type, then assign categories to it from the same page.
If your program doesn't need different writing rules for different kinds of categories, you don't need category types at all: set the rules once at the program level instead (see AI Rules).