  Measurements of the power-law corrections to Bjorken scaling and the behavior
of structure functions in the highly stressed $x_{bj} \to 1$ regime of
electroproduction can lead to new information on the quark-quark correlations
controlling the nucleon wavefunction at far-off-shell kinematics.
Electroproduction on nuclei at $ A > x_{bj} > 1$ is sensitive to hidden-color
components of the nuclear wavefunction. A distinctive dynamical higher-twist
${\cal O}(1/Q^2)$ correction, which is dynamically enhanced at high $x_{bj}$,
can arise from the interference of amplitudes where the lepton scatters from
two different valence quarks of the target. Measurements of the
parity-violating left-right asymmetry $A_{LR}$ in elastic and inelastic
polarized electron scattering at large $x_{bj}$ can confirm the structure of
the quark-quark correlations and other QCD physics at the amplitude level.
