Location of the evolutionary models in an HRD, as in Fig. 1. Each colored circle is one of the 2880 stellar models, forming 192 evolutionary tracks. The colors indicate the error on the inversion. No significant correlation can be seen between the errors on the inferred difference in structure and the position of the model in an HRD. We note that the tracks overlap in this figure, hence the color at location of the target models is not necessarily representative of the reference models themselves.