the long range features in the meson propagators and the short range features in the vertex functions. This separation is discussed in Sect. III. Such a separation may be questioned, but [*a priori*]{} these assumptions should be no worse for the case of CSB potentials then they are for the isospin conserving part of the interaction. Moreover given the lack of rigor in the construction of potential from the underlying field theory, some assumptions must be made in order to make make any connection between $\rho-\omega$ mixing and the CSB potential. Given this, it is highly desirable to make sure that the assumptions are consistent with those made elsewhere in the problem.

It is worth stressing at the outset, that in conventional treatments of meson exchange potentials the off-shell propagator plays no role. This is discussed in Sect. IV where realistic boson-exchange charge symmetric potentials are defined to be those that are consistent with the separation discussed in Sect.III. We show that for models with realistic spectral functions the momentum dependence of the meson propagator can be absorbed into that of the vertex function. An example of an unrealistic momentum dependent $\omega$ self energy is presented.

The ideas of the 