The impression I got, and I'd be happy to have someone help me improve this impression, is that it's a way to craft a CA that behaves the way you want as oppose

The impression I got, and I'd be happy to have someone help me improve this impression, is that it's a way to craft a CA that behaves the way you want as opposed to the traditional approach to studying CA's which involves tinkering with the rules and then seeing what behaviour emerges.