|RRM| as a function of the impact parameter for different azimuthal angles relative to the disc minor axis for inclined galaxies. The filled black circles with solid lines are the measured |RRM| values close to the minor axis of the disc (i.e., |ϕ|< 45°), and the dashed line with filled diamonds give the measured |RRM| values near the major axis of the disc (i.e., |ϕ|> 45°). The error bars of the impact parameter give the standard deviation and those of |RRM| the standard error of the mean.