What precisely are the definitions of 2gen and 3gen? That is,
Is 2gen using R and U, or any two sides? Of course, we can assume that the two sides aren't opposite, as scrambles with only L and R are trivial.
However, is 3gen strictly made of R, U, F?
What about R, U, L, where two of the sides are opposite? Corner permutation is now possible, but edge orientation is still not. Is it like 2.5gen or something?