Inversions of the Γ₁ profile as a function of normalised radius determined from actual solar data. Left panel: subdomain of the method for the Z determination (indicated by the vertical orange lines). Right panel: subdomain of the method for the X determination. The orange curves are associated with reconstructions using FreeEOS, the purple curves are associated with reconstructions using SAHA-S, and the blue and red curves are associated with models M1 and M2 and A1 and A2, respectively.