Help me out- I feel like I would have seen this explained somewhere before on the interwebs, but I can't find it.

When I see a listing for a sprint car chassis, I see an 88/40, or similar listing. What dimensions are these referring to? Is there a preferred 'number' for non-wing vs a wing chassis?

Thanks

(Edit: Nevermind- I didn't try Googling as hard as I thought.)