  Time-averaged two-point currents are derived and shown to be spatially
invariant within domains of local translation or inversion symmetry for
arbitrary time-periodic quantum systems in one dimension. These currents are
shown to provide a valuable tool for detecting deformations of a spatial
symmetry in static and driven lattices. In the static case the invariance of
the two-point currents is related to the presence of time-reversal invariance
and/or probability current conservation. The obtained insights into the
wavefunctions are further exploited for a symmetry-based convergence check
which is applicable for globally broken but locally retained potential
symmetries.
