We do not need a precise, objective legal definition of what is, or isn't DIR. Its perfectly fine to have DIR become a fuzzy concept, incorporating GUE, WKPP, and even AG/5th-D NAUI stuff, x-scooters or gavins, long hose over or under, that's all good. We all dive as a team, we all use the long hose, we all go for the right post first, we all deco horizontally. In the venn diagram over the set of all possible scuba practices there is a set which is definitely DIR, there is a very narrow set of fuzziness and there a huge big swath which is not-DIR.
My sentiments exactly.