Comment on the problem of the off-shellγNNvertex function inedelastic scattering

It is shown that there is an ambiguity in the form of the off-shell $\gamma \mathrm{NN}$ vertex function in $\mathrm{ed}$ elastic scattering. The degree of the ambiguity problem might be reduced by the requirement that the vertex be free of kinematic singularities and the off-shell isoscalar nucleon form factors be analytic.