Plots a) and b) (top) corresponds to NReg, and plots c) and d) (bottom) to SReg. Plots a) and c) (left) show the position of all the measured maser spots, and plots b) and d) (right) present the maser features. On plots a) and c) the dashed vectors indicate the direction of the pPN jet. On plots b) and d) the size of the triangles are scaled by the maser fluxes, and the color scale is related to the velocity. The black lines represent the EVPA and intensity of the linear polarization.