Line predictions for our best-fitting model of DG Tau. The ¹²CO (6−5) and C¹⁸O (2−1) data are taken from Schuster et al. (1993) where their  scale is equivalent to our T_mb scale. The ¹³CO (1−0) is from Kitamura et al. (1996a), and since we were unable to establish a conversion from Jy to K, we compare the line shape only. We have indicated with a thick blue line our fits for a 600 AU disk at an inclination of 25°. Indicated in red is how the (¹²CO, HCO⁺, and HCN) line profiles are affected by the absorption or excess emission from a cold, foreground cloud at a radial velocity of 6.1 km s^-1. No differences are visible for the ¹³CO or C¹⁸O lines. The effect of the foreground cloud on the CN line is not available; but the expected hyperfine line-splitting is calculated.