  We consider the relation between so called continuous localization models -
i.e. non-linear stochastic Schr\"odinger evolutions - and the discrete
GRW-model of wave function collapse. The former can be understood as scaling
limit of the GRW process. The proof relies on a stochastic Trotter formula,
which is of interest in its own right. Our Trotter formula also allows to
complement results on existence theory of stochastic Schr\"odinger evolutions
by Holevo and Mora/Rebolledo.
