We can define so-called pair selection thresholds τ ∆ that have various influences on the treatment of the pair, e.g., the pair selection thresholds τ ∆ CutPNO and τ ∆ CutPairs determine the levels of the PNO truncation threshold τ CutPNO and the pair cutoff τ CutPairs , respectively, at which the pair is treated.