Two-colour diagram for galaxy models, based on the BC03, solar metallicity SSPs, under different prescriptions for their SFH (coloured symbols), superposed on the distribution of rest-frame colours of galaxies of the SUDARE (COSMOS + CDFS) sample (grey scale). The four panels show the models computed with exponentially decreasing SFH (top left), delayed exponential SFH (top right), log-normal SFH (bottom left), and inflating + quenched models (bottom right). The colour and symbols encoding are labelled in each panel. For the log-normal SFH, models with the same t₀ but different value of the τ parameter are plotted with the same symbol (shape and colour). In all panels, filled symbols show models with sSFR ≥ 10⁻¹¹ M_⊙ yr⁻¹, eligible to be classified as star forming objects, while empty symbols show models with sSFR < 10⁻¹¹ M_⊙ yr⁻¹, which would be classified as passive galaxies. The arrow in the bottom right panel shows the direction of the reddening vector.