  We rewrite the system \Delta u - W_u (u) = 0, for u: R^n to R^n, in the form
div T = 0, where T is an appropriate stress-energy tensor, and derive certain a
priori consequences on the solutions. In particular, we point out some
differences between two paradigms: the phase-transition system, with target a
finite set of points, and the Ginzburg-Landau system, with target a connected
manifold.
