User blog comment:Ikosarakt1/Formal definition of tetrational arrays/@comment-5529393-20130329075222/@comment-5150073-20130331135403

My rule A2 use A as the wildcard character for any structure like # does it in the main rules. So if A = X^X^X, A^2 = X^X^X^2, not (X^X^X)^2. If it is confusing, I can use standard #.