I know that I could calculate the left nullspace of A by taking the transpose and then finding the nullspace, but is there a shortcut to find the basis for the left nullspace of A if I know R (rref(A))?

For example,
C(A) = pivot cols of A
C(A^T) = non-zero rows of R
N(A) = special solutions
N(A^T) = ?

I can't find any help on this in my text or the almighty google.