Schematic representation of the geometry of the gas in the central kpc of M31. The graph represents a simplified cross section of the gas disk in the sky plane containing the central black hole, represented by the black cross. The blue part is the main disk, aligned with the galactic disk of M31, the green part represents the ring and the red part shows the nuclear disk. The green cross represents the center of the ring, offset with respect to the nucleus. The dashed part of the red line corresponds to the warped disk, whereas the full lines are stiff components. The dashed black line points to where the disk is supposedly teared. We also show a number of parameters of the modeling: r_w is the distance between the central black hole and the end of the warped region; r_md indicates where the main disk begins; r_r is the inner radius of the ring, as well as the end of the nuclear disk as they are supposed to be from a single structure that teared; w_r is the width of the ring; and r_id is the radius of the stiff disk inside the inner region. The substructures are not to scale for visibility reasons.