Subcategories in eProductivity Reference
November 2, 2010 by Ryan Heathers
What you may not know is that you can also create subcategories in eProductivity Reference. You just need to use the same Main Category\Subcategory format in the 'Category' field of a Reference entry and voila!, subcategory created.
I whipped up a quick screenshot example from my own eProductivity Reference to show this...

Of course, eProductivity Reference is a free download.