  We provide a generalization of the horizontality condition of the usual
superfield approach to Becchi-Rouet-Stora-Tyutin (BRST) formalism to obtain the
nilpotent (anti-)BRST symmetry transformations for all the fields of a four (3
+ 1)-dimensional interacting 1-form U(1) gauge theory (QED) within the
framework of the augmented superfield formalism. In the above interacting gauge
theory, there is an explicit coupling between the 1-form U(1) gauge field and
the complex scalar fields. This interacting gauge theory is considered on the
(4, 2)-dimensional supermanifold parametrized by the four even spacetime
variables x^\mu (with \mu = 0, 1, 2, 3) and a pair of odd Grassmannian
variables \theta and \bar\theta. The above (anti-)BRST symmetry transformations
are obtained due to the imposition of a gauge (i.e. BRST) invariant restriction
on the (4, 2)-dimensional supermanifold. This restriction owes its origin to
the (super) covariant derivatives and their intimate connections with the
2-form (super) curvatures. The results obtained, due to the application of the
horizontality condition alone, are contained in the results obtained due to the
imposition of the gauge (i.e. BRST) invariant restriction on the above
supermanifold.
