Observed [O i], [C ii], CO, and H₂O  line fluxes and ratios (red dots) are compared with predictions from a subsample of disk models from the DENT grid (Woitke et al. 2010; Kamp et al. 2011). Contours encircle 85% of the DENT disks for star luminosity values from 10^-2 L_⊙  to 9 L_⊙  (red, yellow, green, cyan, blue, and black contours). The total errors on the observed values (dotted red lines) are obtained summing the error due to the line signal-to-noise (solid red lines) and the 30% error affecting PACS flux calibration. The subsample of disk models is obtained by selecting M ≤ 2.5 M_⊙, T_eff ≤ 5500 K, L ≤ 9 L_⊙, R_in = R_subl, and dust-to-gas ratio =0.01.