We study basic invariants of submanifolds of solutions) . Two Levi forms exist, and have the same rank r min(n, m). If M is k-nondegenerate with respect to parameters and l-nondegenerate with respect to variables, Aut(M ) is a local Lie group of dimension: dim Aut(M ) n+1+2k+2l 2k+2lmin (n + 1), (m + 1) .Mainly, our goal is to set up foundational material addressed to CR geometers. We focus on n = m = 2, assuming r = 1. In coordinates (x, y, z, a, b, c), a local equation is:with β and β representing the two 2-nondegeneracy invariants at 0. The associated para-CR PDE system: