Band function parameters as a function of the position of the energy break E_break of the 2SBPL function. Each plot shows the parameters of the Band function fitted to a series of spectra simulated assuming the 2SBPL function whose parameter values are marked by the horizontal dashed lines. Top: low-energy slope α_Band (orange symbols) and high-energy slope β_Band (blue symbols). Middle: energy peak E_{peak, Band} (green symbols). Bottom: fit (red symbols). Left: spectrum characterized by a S/N ∼ 21 (fluence ∼3.5 ⋅ 10⁻⁴ erg cm⁻²). Right: spectrum characterized by S/N ∼ 2.7 (fluence ∼3.5 ⋅ 10⁻⁵ erg cm⁻²). Data are represented as circles when the best-fitting model is Band and as diamonds when the best-fitting model is 2SBPL.