Redshift snapshots of the predicted equivalent-width profiles, ${\overline{W}}_r(R)$, of Mg IIλ2796 and O Iλ1302. The redshifts are selected to match the available W_r-ρ data at z > 2 for Mg II and the available f(W) parametrization for O I (Becker et al. 2019). Model uncertainties are propagated from those of f and ϕ. The Mg II data points are taken from Bouché et al. (2012) and Møller & Christensen (2020) (open circles), and Bordoloi et al. (2024) (filled squares), with impact parameters normalized by (L/L^⋆)^β. In the Møller & Christensen (2020) data, W_r is estimated based on the published velocity width, by assuming a simple box profile of a fully saturated line.