Top panel: 3D phase portrait between parity, toroidal magnetic field and the shear proxy (see Eq. (14)) from solution 2. Each of these three quantities is extracted at r/R = 0.85 and 15° latitude. Only the modulation envelope of those quantities is used for plotting, i.e., the primary cycle is removed. The color code represents the magnitude of the parity from −1 in blue to +1 in red. The bottom panel is a Poincaré section in the P = 0 plane, with the inset focusing on one of the four crossing locations. The trajectory therein is space-filling, indicating that the modulation is chaotic (see text).