Gaussian line scans performed on the flux-resolved spectra of IRAS 13224–3809 in the 3–10 keV range in the source rest frame. The line width is fixed to σ_line = 100 eV, and the ordinate axis shows the best-fitting line normalization, with negative values indicating absorption features. The colored contours indicate thresholds in ΔAIC relative to strong and very strong evidence for the inclusion of an additional line, corresponding to ΔAIC = 10 (purple) and ΔAIC = 20 (orange), respectively. These conservative ΔAIC thresholds are adopted to robustly highlight only the most significant structures; the same regions are also recovered when using likelihood-based Δχ² (ΔW) contours commonly adopted in previous analyses.