New fundamental observables are becoming
accessible with the Leading Proton Spectrometers
(LPS) of ZEUS and H1. This enables us to test
more thoroughly the pQCD mechanism of diffractive
Deep Inelastic Scattering (DIS). Calculations of
the diffractive cross-section in the small
Bjorken x limit have been performed. We have
used the microscopic QCD formalism of
diffractive DIS to find higher twist corrections
to the transverse structure functions and predict
the diffractive slope and azimuthal asymmetries.
We establish duality correspondence between
diffraction into low-mass continuum and vector
meson production, and calculate the diffractive
contribution to the spin structure functions.