Left: Example of UV emission line and DLA fitting for JADES-GS-z13-0 (DJA ID 3215_20128771) at z = 12.85. The NIRSpec/PRISM spectrum and associated error are shown in green. The marked UV emission lines were modelled and then superimposed on the intrinsic spectrum before modelling the DLA (solid black line). In the inset, we show a zoom on the Lyα region, with the DLA+IGM model as a solid line, and with 100% neutral IGM only (x_HI = 1.0) as a dashed line. Right: Corner plot of the posterior distributions for the DLA+IGM model, with median, 16th and 84th percentiles marked.