CO velocity-integrated intensity diagrams predicted by non-stationary CJ-type shock models for various pre-shock densities: n_H= 10⁴ (upper left panel), 5 × 10⁴ cm^-3 (lower left panel), 10⁵ (upper right panel), 5 × 10⁵ cm^-3 (lower right panel), and G. The observational data are drawn with filled (empty) squares for a filling factor of 1 (of 0.25). The shock velocity and age are given in each panel, as is the color code.