Injection frequency at the t_p for each GRB. The optical-R frequency is show by the horizontal line. The injection frequency is shown for the homogeneous and wind case with red and blue symbols. GRBs with t_p from the LAT light curve are shown with star symbols. The scaling t^{− 3/2} of the injection frequency is shown for reference (it is not a fit) by the dashed line. Vertical bars, shown only for the red symbols, represent the position of the injection frequency obtained assuming ϵ_B in the range 10^-4−10^-1.