Toomre ((U² + W²)^1/2 vs. V, top-left) and Böttlinger (V vs. U, bottom-left, and V vs. W, bottom-right) diagrams. Filled star symbols stand for candidate stars in the halo, filled black circles for the thick disc, grey filled squares for thick-thin transition disc, and open circles for the thin disc. Colour-coded open circles are stars in young SKGs as by SteParKin (legend shown in the top-right). Filled crosses show the center of each group. In the Toomre diagram, the dashed lines indicate constant space velocities with respect to the local standard of rest, $v={\left(U_{\text{LSR}}^2+V_{\text{LSR}}^2+W_{\text{LSR}}^2\right)}^{1/2}$, at 25, 50, 100, 150, and 200 km s⁻¹. In the Böttlinger diagrams, the dashed lines indicate Eggen’s young disc population criteria.