  In a covariant gauge we implicitly assume that the Green's function
propagates information from one point of the space-time to another, so that the
Green's function is responsible for the dynamics of the relativistic particle.
In the light front form, which in principle is a change of coordinates, one
would expect that this feature would be preserved. In this manner, the
fermion's field propagator can be split into a propagating piece and a
non-propagating (``contact'') term. Since the latter (``contact'') one does not
propagate information, and therefore, assumedly with no harm to the field
dynamics we wanted to know what would be the impact of dropping it off. To do
that, we investigated its role in the Ward identity in the light front.
