I wish to create something similar to the following table
where Ozeki and Yokozuna are categories. I, II, III, etc. are sub categories, and Azuma, Santoro, Kenzo are items in the first column. The cells are to be inputted either numerical values or strings.
I am quite familiar with how to create something like
but clueless as to how to add that first "grand" category. I don't even know what type of table I should use.
A minimal example should suffice. Outer border is not needed.