Average of computed dipole (ℓ = 1) period spacings, $\overline{\mathrm{\Delta }{\mathrm{\Pi }}_k}$, in terms of effective temperature, for different stellar masses in solar units (numbers at top right corner of each panel) and thicknesses of H envelope (see Table 4 of Uzundag et al. 2023, for the specific values of log(M_H/M_★)) drawn with different colours. In each panel, we include numbers along two curves, which correspond to the value of log(M_H/M_★) for the thickest and the thinnest H envelopes for each stellar mass value. The location of WD 1310+583 is emphasized with a circle with error bars with effective temperatures T_eff = 10 131 ± 260 K (red symbol; Leggett et al. 2018), T_eff = 10 313 ± 111 K (blue symbol; O’Brien et al. 2024), and T_eff = 11 660 ± 163 K (green symbol; Section 2 of this work), and a period spacing ΔΠ = 40.51 ± 2.00 s (Section 5).