[en] The full three-dimensional Maxwell--Vlasov system is solved as a boundary value problem for systems contained by plane, perfectly reflecting boundaries. The spatial behavior of the fields seems to contradict some commonly made assumptions. In particular, for low frequency, ωvery-much-less-thanω/sub p/, and typical plasma densities, all components of the electric and magnetic fields decay to zero on a scale which is no larger and 0.05 cm