And all this time, I thought the language hierarchy, and it's correspondence with math/logic categories, was the real theory. UG is kind of an irrelevant side p

And all this time, I thought the language hierarchy, and it's correspondence with math/logic categories, was the real theory. UG is kind of an irrelevant side point, sort of an argument between "strong" vs "weak". Type 0 - Recursivey enumerable. Type 1 - Context-sensitive. Type 2 - Context-free. Type 3 - Regular. As all languages fall into one of those 4 categories, and no other (so far), that seems to me to be THE definition of "following the rules" to an extreme. Once you've identified which category a language is in, the word order and semantics are pretty damned irrelevant, as any experience computer programmer can attest (Java vs C++, Python vs Ruby, etc).