Relationships among the eight fitting parameters. For each event, the four parameters of the peak flux spectrum (Eq. (9)) are plotted on the x-axes, while the four parameters of the integral fluence spectrum (Eq. (3)) are plotted on the y-axes. Solid dots are parameters of GLE events, while parameters of other SEP events are represented by hollow circles. In each panel where the R² value is larger than 0.1, the red line represents the linear regression curve between two parameters for all events, and the corresponding linear regression function is shown in the legend. The shaded area represents the confidence interval for one standard deviation. The red dashed line in panel l represents the function of |γ₂|=γ.