A Drazin invertible Hilbert space operator T ∈ B(H), with Drazin inversewhere T 1 is similar to an invertible normal operator and T 0 is nilpotent. Using this representation, we have a keener look at the structure of [(n, m)DN ] and [(n, m)DQN ] operators. It is seen that T ∈ [(n, m)DN ] if and only if T ∈ [(n, m)DQN ], and if [T, X] = 0 for some operators X ∈ B(H) and T ∈ [(1, 1)DN ], then [T * d , X] = 0. Given simply polar operators S, T ∈ [(1, 1)DN ] and an operator A = T C 0 S ∈ B(H ⊕ H), A ∈ [(1, 1)DN ] if and only if C has a representation C = 0 ⊕ C 22 .