  By separating the gluon field into physical and pure-gauge components, the
usual Poincar\'e subalgebra for an interacting system can be reconciled with
gauge-invariance when decomposing the total rotation and translation generators
of QCD into quark and gluon parts. The gauge-invariant quark/gluon parts act as
the generators for the gauge-invariant physical component of the quark/gluon
field, not the full quark/gluon field which also contains the gauge degrees of
freedom. We clarify that the naive canonical decomposition of generators, while
trivially respecting the Poincar\'e subalgebra, might not give a completely
gauge-invariant quark-gluon structure of the nucleon momentum and spin, though
limited invariance within a certain gauge class can be proven.
