Position-velocity (PV) diagrams along the major axis for HCO⁺(3-2) (top, PA = 216°) and HCN(3-2) (bottom, PA = 217°) in the B6SB dataset. The colour map and black contours represent the data, and the cyan contours represent the model. Both sets of contours are drawn at [1, 2, 4, 8]×1.5 mJy/beam. Overlaid on the PV diagrams are also the fitted line-of-sight velocities V_LOS = sin(i)×V_rot using cyan circles and the theoretical Keplerian profile of a central SMBH with a mass of M_• = 1.7 × 10⁶ M_⊙ (Greenhill et al. 2003) using a solid red curve. The size of the torus, which is barely resolved in B6SB, is indicated on the edges of each panel using vertical cyan markers. A white arrow is drawn in both panels to indicate the location of a <  − 100 km s⁻¹ blueshifted emission component in the data that is not replicated by the model. The synthesised beam sizes are shown in the bottom left as white bars.