  As a consequence of motions driven by external forces, self-fields originate
within an electron bunch, which are different from the static case. In the case
of magnetic external forces acting on an ultrarelativistic beam, the
longitudinal self-interactions are responsible for CSR (Coherent Synchrotron
Radiation)-related phenomena, which have been studied extensively. On the other
hand, transverse self-interactions are present too. At the time being, several
existing theoretical analysis of transverse dynamics rely on the so-called
cancellation effect, which has been around for more than ten years. In this
paper we explain why in our view such an effect is not of practical nor of
theoretical importance.
