Line profile predictions for T _⋆   = 2000 K, L _⋆   = 3000 L_⊙, d = 300 pc, f_H,CO  = 1 × 10^-4, ¹²C/¹³C = 10, R_inner  = 3 R _⋆ , Ṁ  = 1 × 10^-7 M_⊙ yr^-1, v_∞  = 10 km s^-1 for a beam width of 10′′. The soft-parabola fit is plotted in dashed grey/light blue lines. For the high-J excitation lines one can see both the stellar and dust continuum and the acceleration zone (the narrow peaks around the line centres).