Line shift, |v_los|, versus velocity dispersion, σ_los, of the ionized gas. Comparison of observations with the CCA model (Gaspari et al. 2018). The purple shaded region show ensemble (single spectrum) predictions from the CCA simulations at 1σ, 2σ, and 3σ confidence intervals. Data points from our sample are shown with yellow, red, and green circles for filamentary, extended, and compact disks, respectively. Whereas data from the literature are displayed with purple circles (Gaspari et al. 2018). This diagnostic is also known as kinematical plot, in short “k-plot”.