Two proofs have been shown for P systems with active membranes in previ-
ously published papers, demonstrating that these P systems can solve in polynomial time
exactly the class of problems PSPACE. Consequently, these P systems are equivalent
(up to a polynomial time reduction) to Second Machine Class models as the alternating
Turing machine or the PRAM computer. These proofs were based on a modified definition of uniform families of P systems. Here we demonstrate that the results remain valid
also in the case of standard definitions
