  For a generalized Kummer variety X of dimension 2n, we will construct for
each 0 < i < n some co-isotropic subvarieties in X foliated by i-dimensional
constant cycle subvarieties. These subvarieties serve to prove that the
rational orbit filtration introduced by Voisin on the Chow group of zero-cycles
of a generalized Kummer variety coincides with the induced Beauville
decomposition from the Chow ring of abelian varieties. As a consequence, the
rational orbit filtration is opposite to the conjectural Bloch-Beilinson
filtration for generalized Kummer varieties.
