  We investigate the properties of localized anomalous U(1)'s in heterotic
string theory on the orbifold T^6/Z_3. We argue that the local four dimensional
and original ten dimensional Green-Schwarz mechanisms can be implemented
simultaneously, making the theory manifestly gauge invariant everywhere, in the
bulk and at the fixed points. We compute the shape of the Fayet-Iliopoulos
tadpoles, and cross check this derivation for the four dimensional auxiliary
fields by a direct calculation of the tadpoles of the internal gauge fields.
Finally we study some resulting consequences for spontaneous symmetry breaking,
and derive the profile of the internal gauge field background over the
orbifold.
