C III and C IV lines in the HST/COS spectrum of WD 0111+002 (black) compared with three log g = 7.7 models with different T_eff: 53 000 K (blue dashed), 58 000 K (red), and 63 000 K (green dashed). Red wavelength labels indicate forbidden C IV line components (Werner et al. 2016). Also indicated are Zn lines near the C III multiplet at 1175 Å. The vertical bar indicates 20% of the continuum flux.