  An ambiguity inherent in the partial integration procedure leading to the
Bern-Kosower rules is fixed in a way which preserves the complete permutation
symmetry in the scattering states. This leads to a canonical version of the
Bern-Kosower representation for the one-loop N - photon/gluon amplitudes, and
to a natural decomposition of those amplitudes into permutation symmetric gauge
invariant partial amplitudes. This decomposition exhibits a simple recursive
structure.
