[Mg/Fe] − [Fe/H] distribution of A2A and APOGEE stars in intervals of height from the plane (|Z|, kpc) and distance along the bar (|X_bar|, kpc). The stars are required to have |Y_bar| < 1 kpc. The point colour gives the Gaussian kernel density estimate. The dashed lines separate the different regions in the parameter space generally populated by the halo, thin disk, and thick disk (defined in the lower-leftmost plot; see text). The number of stars composing each plot (A2A RC stars + APOGEE stars) is given in the lower left corner of each plot.