Four scenarios proposed for the central region in M31, represented by their schematic transversal cut. Grey lines correspond to transition zones, blue lines to the main disk, red lines to the warped nuclear disk, and green lines to the inner ring. When two structures are decoupled, two distinct velocity components may be observed along the same line of sight, while when they are linked by a transition zone, there would be a single wide velocity component. Top-left: Scenario 1, where the nuclear and main disks are linked. The inner ring is decoupled, implying two velocity components along a line of sight. Top-right: Scenario 2, where the nuclear disk is linked to the inner ring. The main disk is decoupled, with possibly two velocity components on some line of sights. Bottom-left: Scenario 3, where the three structures are decoupled, implying distinct velocity components along a line of sight. Bottom-right: Scenario 4, which is the same as scenario 3, but there is now a link between the main disk and inner ring, limiting the occurrence of distinct velocity components.