Charges as null plane integrals over tensor densities

For the purpose of defining null plane charges, densities transforming as tensors under the Lorentz group are classified as very good, good, bad and very bad. In the general case of nonconserved tensors in a theory with interaction, it is argued that, in the presence of a mass gap, null plane integrals of members of the first two classes are expected to define symmetric charge operators on dense sets of states; for the last two classes they are not. The existence of null plane charges depends on the asymptotic behavior of off mass shell scattering amplitudes. It is shown that s 1n s behavior is the maximal growth consistent with the existence of null plane charges associated with currents.