Diagrams of χ² minimization of the comparison between 1 × 200 × 200 LVG grids modeled with sets of parameters (, N_CO, T) and observations of ¹²CO and ¹³CO lines toward the boxes corresponding to the shocked clump (a−c), ring-like structure (d), cloudlet (e), ambient cloud (f), and shocked knot (g) defined in Table A.1. Shades of green represent the areas of minimum χ² corresponding to the minimization of the specific intensity of the ¹²CO(3–2), ¹²CO (2–1), and ¹²CO(1–0) lines (first term introduced in Eq. (12)), and the shades of pink represent the areas of minimum χ² corresponding to the minimization of ¹³CO lines (second term introduced in Eq. (12)). The filled contour levels are log₁₀ (χ²) = [0.6, 1, 1.5, 2]; the first contour level is highlighted by a solid black line. Hatched areas represent the intersection between the previously described sets of contours, defined by (Eq. (12)) for boxes a−g, respectively.