Notes. Radial range of 5 <r< 13 kpc was used for fitting. For a given age subsample, only minimal variations are seen with distance from the disk. However, gradients in the total population can vary strongly because of (i) the predominance of young stars close to the disk plane and old stars away from it (as illustrated by the rectangular symbols in Fig. 10); and (ii) the more concentrated older stellar component. It should be kept in mind that the variations of [Fe/H] and [Mg/Fe] with radius are rarely well fitted by a single line in both the observations and our model (see Fig. 10). Therefore, non-negligible variations in the estimated gradients should be expected with a change in the radial range used for fitting.