DALI model with a mass of 0.2 M_⊙. The disk is divided into rings based on the R_90% of the isotopologue. The rarest isotopologue (¹³C¹⁸O) is in the center, while ¹²CO is in the outer ring. The six panels on the right show the abundance of the six ray-traced CO isotopologues. The vertical colored lines correspond to the colors of the circles on the left. The white lines indicate the τ = 1 surface, and the black lines indicate where 50% and 95% of the emission is coming from.