Sometimes it's nice to be able to see all combinations of rule context (library, patron category, itemtype) at a glance.

This isn't the default however, as it can quickly become overwhelming, so we only display the explicitly defined rules by default. 

To quickly calculate the number of rows in the table..  assuming we stick to display the library levels on their own pages, the tables for each would contain (number of patron categories + 1) * (number of item types + 1), so you can see how the table grows quickly.. but I think think it would be a useful view option.