Un-normalized survival function of the fluence distributions (red line) for the bursts recorded at the end of F21 activity window (Zhang et al. 2022). The gray rectangles mark the regions in the fluence–burst number parameter space that contain bursts excluded from the PL fit (see Section 4.3.2 for details). The colored rectangles contain bursts included in the fit; the color represents the steepness of the best-fit power-law index (PLI) ranging from light yellow (α_m = −0.5) to dark blue (α_m = −2.5). Light blue bands of progressively lighter shades in the background correspond to regions containing 10, 100, and 1000 bursts.