Same as in Fig. 3, except the projections were calculated at conditions p_R = 0 and ṗ_R > 0 on the z–V_z plane. Red, cyan, and green dots show the projections of three periodic orbits on the Poincaré map corresponding to the 2/1, 4/1, and 6/1 resonances, respectively. The large island of orbits oscillating around the centre at z = 0 kpc and V_z = 103.0 km s⁻¹ (black dot) is related to the strong 1/1 resonance (see later Fig. 7).