Questions about the transition reduce matrix between bound states

(1) For the radiation transition from the initial (higher) bound state Psi_i to the final (lower) bound state Psi_f, what does the sign (positive or negative) of the corresponding the transition reduced matrix determine?

(2) When the initial and final states are determined, the product of reduced matrix elements with different multi-pole transitions must be positive ? or positive or negative ? Specifically speaking , for Li-like ions, the sign of * must be positive? or it can be positive or negative？