Left: standard 1σ envelope of the binary-system age-relative error in dependence on the mass of the primary star (solid black), compared with the same quantity obtained by sampling from the standard grid and reconstruction on a grid of stellar models computed without microscopic diffusion (dashed red). Middle: same as the left panel, but in dependence on the mass of the secondary star. Right: same as the left panel, but in dependence on the system’s mass ratio q.