Unreachable nonterminals.

[modulovalue]

As a response to your unreachable nonterminals comment:

I'm currently visualizing it like this:

Notice how F and G are self-contained and do not connect to the other parts of the grammar, therefore, they are unreachable. I think it would be more informative to expose collections of SCCs rather than single unreachable nonterminals.

Edit: correction, of course, I meant to say connected components, not strongly connected components.