Schematic view of the interpretation proposed for the CO velocities observed. The inner disc is presented with a PA of 70 deg and an inclination of 43 deg. The inner ring is superimposed with a similar inclination but a position angle of  −35 deg. The straight line indicates the position of the major axis of the main disc inclined by 77 deg with a PA of 35 deg. The bars labelled “N” and “E” have a length of 150 pc. The near (resp. far) sides of the two components are coloured (resp. kept white). The red (resp. blue) colours correspond to the redshift (resp. blueshift) relative to the systemic velocity.