Portion of X-shooter UVB spectrum of J0015+1842 (black, with uncertainties in grey). Horizontal blue segments connect rotational levels (short tick marks) from a given Lyman (L) or Werner (W) band of H₂ for the central H₂ component. The same is shown in grey for the two other components, but they are not labelled for visibility. The overall model (MCMC-based) spectrum is over-plotted in red, with contribution from non-H₂ lines (H I and metal lines) shown as a dotted purple line.