Inclusive diffraction and factorisation tests at HERA:
New measurements are presented of inclusive virtual photon dissociation in
deep inelastic scattering (gamma* p -> X p).
Among other approaches, the data are interpreted in terms of
diffractive parton density functions, which in turn are applied to the
prediction of diffractive hadronic final state obserables. The degree of
success of these comparisons in
deep inelastic scattering, photoproduction and proton-proton
collisions is assessed and interpreted in terms of a rapidity gap survival
probability which is smaller than unity due to rescattering effects.