The different components of the angular momentum, L = r x p, do not commute with each other, but satisfy the commutation relation [L_a, L_b] = i hbar epsilon _abc L_c. The individual components do commute with L² = L_x² + L_y² + L_z² . Thus, it is possible to simultaneously specify the eigenvalues of L² and any one of the angular moment components such as L_z, which is the conventional choice.