Distribution of V as a function of Galactocentric distance (R_gal). Each marker corresponds to a 10^° × 10^° × 1.29 km s⁻¹ tile on the left-hand panel of Fig. 2. Colors represent the central Galactic longitude (l) of each tile. The black solid line shows the V mean value in 1-kpcwide R_gal bins. The dashed vertical line indicates the radius of the Solar orbit, R_⊙ = 8.15 kpc. The solid horizontal line marks V = 0, which corresponds to no preferential orientation either parallel or perpendicular to the Galactic plane. The dashed horizontal lines indicate V = ± 2.87, which correspond to the 3σ significance levels for preferential orientation parallel or perpendicular to the Galactic plane, respectively.