Warm absorber transmission model (top) and lag-energy spectrum (middle and bottom) for the computed grid of distances. The reference band to compute the lag-energy spectrum is a broad EPIC-pn band (1.5−10 keV). We note that a negative lag indicates a soft lag, which means that the band of interest lags the broad reference band. This helps to easily match the lag-energy spectrum to the absorption features in the energy spectrum.