Dipole (upper panel) and quadrupole (lower panel) average of the computed period spacings, , assessed in a range of periods that includes the periods observed in PG 1351, shown as curves of different colors according to the different stellar masses. We consider the effective temperature T_eff = 26 010 ± 1536 K (Bergeron et al. 2011), and the possible period spacing values derived from the four periods of PG 1351 according to Table 9. We include the error bars associated with the uncertainties in and T_eff.