Rebinned HEG spectra of the different dipping stages of ObsID 8525. For clarity, the non-dip spectrum (orange, S/N ≥ 13) is scaled by afactor of 8, the weak dip spectrum (red, S/N ≥ 15) by a factor of 4, and the dip spectrum (violet, S/N ≥ 15) by a factor of 2. The strong dip spectrum (blue, S/N ≥ 17) is not scaled. The box denotes the region containing the Si and S lines. The color scheme is the same as in Figs. 1 and 3.