  Including destructively interfering off-diagonal transitions of
diffraction-dissociation type, we arrive at a formulation of GVD for exclusive
vector-meson production in terms of a continuous spectral representation of
dipole form. The transverse cross-section sigma_T for gamma* p -> V p behaves
asymptotically as 1/Q^4, while R_V = sigma_L/sigma_T becomes asymptotically
constant. Contributions violating s-channel helicity conservation stay at the
10-15% level established in low-energy photoproduction and diffractive
hadron--hadron interactions. The data for phi- and rho-meson production for 0
\lsim Q^2 \lsim 20 GeV^2 from HERA are found to be in agreement with these
predictions.
