Model correlations of the γ-ray-to-radio flux ratio vs. optical luminosity along sequences varying individual parameters. Each sequence represents the effect of a variation of one individual base parameter. The legend in the top left indicates the parameters varied along the sequences. Filled symbols indicate SEDs characteristic of FSRQs, while open symbols indicate sequences of SEDs characteristic of BL Lacs. The long-dashed line marks the power-law correlation that best fits the observational data. The sequences marked in blue dashed line (squares) correspond to the sequences of SEDs shown in Figs. 6 and 7 (see also Tables 2 and 3).