what's the real meaning of phase=331, 332, 333 in pardiso solver

In pardiso solver, the parameter phase means the solver execution steps.

If Ax=b, and A is a Real and symmetric indefinite matrix, then P*A*P'=LDL'.

For example, phase=332, only diagonal substitution is executed(Dx=b), and if b is an identity matrix, x will be inverse of D.

But, the result is not. What's the matter, and what's the real meaning of phase=331, 332, 333.

Thank you!