3.1.2.1. For all braking rates between 0.15 and 0.80 in the case of vehicles of category N1 with a laden/unladen rear axle loading ratio not exceeding 1.5 or having a maximum mass of less than 2 tonnes, in the range of z values between 0.3 and 0.45, an inversion of the adhesion utilization curves is permitted provided that the adhesion utilization curve of the rear axle does not exceed by more than 0.05, the line defined by the formula k = z (line of ideal adhesion utilization in diagram 1A of this annex). a0c0