Comparison of the VSF between Nobeyama H¹³CO⁺ (1–0) data and the model. The red line and points indicate the VSF of the Nobeyama H¹³CO⁺ (1–0) centroid velocity. The black line and points indicate the VSF of the modeled fragmenting filament. Blue, green, and dashed blue lines indicate the VSF of the models in which only the velocity gradient along the r direction, the velocity gradient along the z direction, and the oscillation are taken into account, respectively. The typical uncertainty of the observed VSF is 0.08 km s⁻¹.