It is shown that the N=3 harmonic-superfield equations of motion are
invariant with respect to the 4-th supersymmetry. The SU(3) harmonics are also
used to analyze a more flexible form of superfield constraints for the Abelian
N=4 vector multiplet and its N=3 decomposition. An alternative unusual
representation of the N=4 supersymmetry is realized on infinite multiplets of
analytic superfields in the N=3 harmonic superspace. U(1) charges of
superfields in these multiplets are parametrized by an integer- valued
parameter which plays the role of the discrete coordinate. Each superfield term
of the N=3 Yang-Mills action has the infinite-dimensional N=4 generalization.
The gauge group of this model contains an infinite number of superfield
parameters.Comment: Latex file, 16 page