I've always thought that it wasn't possible to have subcategories for only certain categories in
a view. It was all or nothing. I discovered that you can in fact do this.
To do this, there is NO subcategory column in the view and you do NOT use a Subcategory field in the document. The trick is to use the "\" character in your Category field. For example, if I had a category called "Section 1" and I wanted to have subcategories "A" and "B", I would assign documents the categories "Section 1\A" and "Section 1\B" The text before the "\" is the category and the text after is the subcategory.
This was first published in January 2002