Model correlations of the γ-ray-to-optical flux ratio vs. radio luminosity along sequences varying L_D (for quasars, with f_j = const.) and L_j (for BL Lacs), keeping the magnetic field at equipartition (squares), and varying B (downward triangles). Filled symbols indicate SEDs characteristic of FSRQs, while open symbols indicate sequences of SEDs characteristic of BL Lacs. The sequences marked in blue dashed line (squares) correspond to the sequences of SEDs shown in Figs. 6 and 7.