  We explore the consequences for diffractive production, gamma* p --> X p, in
deep inelastic scattering at low values of x\sim Q^2/W^2 <<1 that follow from
our recent representation of the total photoabsorption cross section,
sigma_{gamma* p}, in the generalized vector dominance/ color dipole
picture(GVD/CDP) that is based on the generic structure of the
two-gluon-exchange from QCD. Sum rules are derived that relate the transverse
and the longitudinal (virtual) photoabsorption cross section to diffractive
forward production of q q-bar states that carry photon quantum numbers
("elastic diffraction"). Agreement with experiment in the W^2 and Q^2
dependence is found for M_X^2/Q^2<<1, where M_X is the mass of the produced
system X. An additional component ("inelastic diffraction"), not actively
contributing to the forward Compton amplitude, is needed for diffractive
production at high values of M_X. Our previous theoretical representation of
the total photoabsorption cross section sigma_{gamma* p}=sigma_{gamma* p}(eta),
in terms of the scaling variable eta=(Q^2+m_0^2)/Lambda^2(W^2) is extended to
include the entire kinematic domain, x=<0.1 and all Q^2 with Q^2>=0, where
scaling in eta holds experimentally.
