Categories groups the top-level anchor entity for each of this atlas own entity types, one per type, the page a reader lands on when browsing branches, concepts, figures, institutions, milestones, practices, programs or sources as a whole. Belongs here: the single anchor entity for a type, carrying the prose that explains what the type is and how it is organized underneath it. Does not belong here: the sub categories that divide a type into groups, filed under Subcategories, or the member entities themselves, filed under their own type.