Example of a Case A and Case AB mass transfer episode for a typical binary model in our grid. The initial donor mass, mass ratio and orbital period of the model are 17.8 M_⊙, 0.8 and ∼2.7 d respectively. Various quantities are plotted as function of time, with t = 0 corresponding to the ZAMS stage of both stars. (a) central helium mass fraction of donor (red) and accretor (blue). (b) ratio of donor and accretor radius to their Roche lobe radii. (c) donor and accretor mass. (d) mass transfer rate Ṁ_t (red solid line), effective mass accretion rate Ṁ_a (blue solid line), and wind mass loss rates of donor (−Ṁ_w,d, red dotted line) and accretor (−Ṁ_w,a, blue dotted line), respectively. (e) surface helium mass fraction. (f) surface nitrogen enhancement factor. (g) ratio of rotational to orbital angular velocity. (h) orbital period (solid black line), and the orbital period our model would have obtained if the mass transfer would have been fully conservative (dashed black line).