  We present a unified description of the relativistic piNN and gamma-piNN
systems where the strong interactions are described non-perturbatively by
four-dimensional integral equations. A feature of our approach is that the
photon is coupled in all possible ways to the strong interaction contributions.
Thus the hadronic processes NN -> NN, NN -> pid, pid -> pid, etc. and
corresponding electromagnetic processes NN -> gamma-NN, gamma-d -> NN, gamma-d
-> pid, ed -> ed, ed -> e'pid, etc., are described simultaneously within the
one model of strong interactions. Our formulation obeys two and three-body
unitarity, and as photons are coupled everywhere in the strong interaction
model, gauge invariance is implemented in the way prescribed by quantum field
theory. Our formulation is also free from the overcounting and undercounting
problems plaguing four-dimensional descriptions of piNN-like systems. The
unified description is achieved through the use of the recently introduced
gauging of equations method.
