  Wandzura-Wilczek (WW) relations between matrix-elements of bilocal light-ray
operators have recently regained interest in connection with off-forward
scattering processes. Originally derived for matrix elements over leading-twist
operators, their generalization to off-forward and exclusive processes gets
complicated by the presence of higher-twist operators that are total
derivatives of leading-twist ones and do not contribute to forward-scattering.
We demonstrate that, for exclusive matrix-elements, the inclusion of these
operators into WW-relations is essential for fulfilling constraints imposed by
the conformal symmetry of massless QCD.
