Secondary critical lines in the simulated data sets. The yellow lines in the left and right panels show examples of critical lines with θ_E >  θ_E, cut, classified as “singles” and “groups,” respectively. From the upper to the bottom panels, the critical lines (for z_s = 6) are overlaid onto the convergence maps of simulated clusters in the 10x, 1xRF18, and 1xR15 samples. The value of the corresponding Einstein radius is reported in each panel.