Example of a spectrum best fitted by a 2SBPL (i.e. three power laws smoothly connected at two breaks). The data correspond to the time interval 7.17–8.19 s from the trigger of GRB 180720. The best fit values of the 2SBPL model parameters are α₁ = −0.71, E_break = 93.62 keV, α₂ = −1.47, E_peak = 2.42 MeV, and β = −2.38. The different instruments are colour-coded as shown in the legend. The two dashed lines show, for comparison, the power laws (with the photon indices) predicted by synchrotron emission. Data-to-model residuals are shown in the bottom panel.