Keck/LRIS spectrum of J0546+0836 shifted to rest wavelength and compared to our final model (red graph) with T_eff = 95 000 K, log 𝑔 = 5.5, O = 0.90, and C = 0.10 (mass fractions). The spectrum is dominated by oxygen lines from O IV in emission (formed in a stellar wind and therefore not reproduced by our static model) and O V in absorption, plus the O VI absorption doublet at 3411/34 Å and two wind-emission lines of O III (3962 and 5592 Å). We note, in particular, the (highly excited) Rydberg lines from O V (which are not modeled) indicated by the thick horizontal black bars with respective principal quantum numbers. Small O V labels with question marks indicate probable O V lines in the observation that are nevertheless not included in the model atom. See the main text for the meaning of the colors of the O V line labels. The only other species identified is carbon; e.g., the C IV multiplet at 3690 Å. The C IV emissions (e.g., the doublet at 5801/12 Å) are also formed in the wind.