Comparison, for the 12 Å wide spectral range 4237–4249 Å, between the observed limb/disk-center ratio spectrum R (SS3, solid curve in the middle panel) and the model of R, overplotted as the dashed curve. The bottom panel gives the difference between the solid and dashed curves, on the same scale as used in the middle panel, to allow a direct comparison. The top panel shows the intensity spectrum (SS1) at disk center with line identifications.