I looked at the different mods, and I don't see one that can do the following:

Author adds a record under Category A;
Category includes subcategories 1 through 9;

Then another record is added under category B;
But!... Subcategories for Category can only be 10 through 19

I am trying to have an author choose a category, and when he does, only the subcategories belonging to that category will show. Is this possible?