  We present the microscopic QCD evaluation of the secondary reggeon
contribution to diffractive DIS. It is shown that the interference between
Pomeron and Reggeon enters in the maximal possible way. In the region of large
$\beta \simeq 1$ it is shown, that the structure functions of the Reggeon and
Pomeron as well as the Reggeon-Pomeron interference SF have a universal $\sim
(1-\beta)^2$ behaviour.
