Comparisons of synthetic on-axis spectra and transverse PV cuts at z_cut = 225 au for selected pairs of quasi edge-on models that differ by only one parameter at a time. In red, we show the reference model with i = 87°, r_out = 8 au, α = − 2 (see Eq. (8)), θ_b = 225 au, λ_BP = 5.5, and (and M_⋆ = 0.1 M_⊙, r_in = 0.25 au). In blue, we show the same model with only one parameter value changed (as labelled in each panel). Panel e: reference solution L5W17 replaced by L5W30 (in magenta) so that only λ_BP differs in the comparison (in blue: L13W30). Velocity and angular resolutions are pictured by filled rectangles. The flow is unresolved transversally except when θ_b = 45 au (panel d).