Basic (black) and interpolated (red) main sequence tracks at Z_init = 0.014, in the mass range between 0.5 and 2 M_⊙ where the morphology of the tracks differs most from one track to the next. The interpolated tracks are obtained by interpolating in mass the two encompassing basic tracks. The masses of the tracks are indicated on the figure except for tracks between 1.1 and 1.3 M_⊙ where tracks are equally spaced with mass steps of 0.02 M_⊙.