Because there are thousands of named features on the Moon we have split them into 21 categories: Albedo, Apollo Landing Site, Catena, Craters A-C, Craters D-H, etc. Specific Feature - Immediately to the right of each category name is a pull-down-menu of all the features within that particular category.
(we; have split; them; into 21 categories) (Immediately to the right of each category name; is; )
we Immediately to the right of each category name
have split is
them into 21 categories