Asymmetry parameters a_ℓ, |m| depending on the inclination angle of the field β in case (a) or on the offset of a magnetic field in the case (c) in Fig. 1. The offset z_o of the field is given relative to the radiative zone radius. The pink region indicates, on each panel, the domain for which both an inclined dipole and an offset dipole can yield to the same asymmetry parameter. The blue and red stars show the minimum and maximum offsets measured from the combination of studies by Vennes et al. (2017), Hardy et al. (2023a,b), Hollands et al. (2023). J0942+2052 has an offset of −0.01 (Hardy et al. 2023b) and J0017+004 of 0.40 (Hardy et al. 2023a).