Core intensities for the four selected lines and different calculation methods (solid 3D NLTE, dashed LTE, and plus signs 1D NLTE; the vertical lines are as in previous figures). Each panel pair shows the intensities of a single line for a formal solution with Stokes I only (i.e. no Zeeman splitting; panels a), c), e), g)) and one considering the full Stokes vector (panels b), d), f), h)) as indicated above each panel. Note the x-scale in the left panels of each pair (Stokes I only) is inverted to provide a clearer comparison of the intensities in the FS interior.