Position-velocity diagrams obtained along two nearby north-south axes for the ¹²CO J = 3−2 line emission. In the plot above, the axis crossed the center of the innermost ring (0.03′′ eastward), in the one below the center of the outermost ring (i.e., 0.3′′ eastward). In the right bottom corner of both boxes we plot two small rectangles to show the resolutions, similar to those in Fig. 9. Colored solid lines are plotted to show the different position-velocity gradients. More details can be found in Sect. 6.