Distribution of photon indices describing the spectrum below the peak energy, for the merged sample studied in O17 and this paper. The green histogram shows the indices α₂ describing the spectrum between E_break and E_peak. The blue and red histograms show the distribution of for the same sample of spectra, obtained when the analysis is performed without including XRT. The red histogram denotes cases where the best model is a CPL, and the blue histogram cases where the best-fit model is a single PL.