The aircraft envelope starts from the origin so v = 0 and n = 0, but the gust envelope starts at v = 0 and n = 1 because we have n = 1 in straight and level flight. The gust envelope is superimposed over the aircraft envelope to give reference points. Vb, the design gust load decreases linearly from MSL to altitude.

If L = 0 then n = 0. Zero divided by anything is zero. You will be weightless, like in a bunt.