Upper panels: examples of the continuum-subtracted lines of DG Tau used in the fitting procedure. Different lines are depicted with different colors according to the labels. For a better visualization, some fluxes have been multiplied by a constant as indicated. The [O I]630 profile, which is taken as a reference in the fitting, is shown for comparison in each panel. Middle panels: de-reddened flux ratios with respect to [O I]630 computed in bins of 20 km s⁻¹. Colors have the same meaning as in the top panels. Bottom panels: gas parameters (T_e, n_e, x_e, n_H) plotted as a function of the bins of velocity. The error bars correspond to models whose χ² is up to 30% higher than that of the best fit. The green vertical dotted line marks the position of the rest velocity.