Upper panel: normalised mass fraction profiles for He (dash-dots),Fe (solid), and Ni (dashes) vs. temperature. The grey area denotes the superficial convective zone, and the age, counted from the pre-MS, is shown in the upper left. The dotted line recalls the initial content. Lower panel: Rosseland mean opacity profile at the current age for the diffusion model (thick solid line) and the homogeneous model (thin solid line). The thin dashed line shows the profile of the homogeneous model with local enhancement according tothe method of DPW17.