  The forward-jet cross section in deep inelastic ep scattering has been
measured using the ZEUS detector at HERA with an integrated luminosity of 6.36
pb^-1. The jet cross section is presented as a function of jet transverse
energy squared, E(T,jet)^2, and Q^2 in the kinematic ranges
10^-2<E(T,jet)^2/Q^2<10^2 and 2.5 10^-4<x<8.0 10^-2. Since the perturbative QCD
predictions for this cross section are sensitive to the treatment of the
log(E_T/Q)^2 terms, this measurement provides an important test. The measured
cross section is compared to the predictions of a next-to-leading order pQCD
calculation as well as to various leading-order Monte Carlo models. Whereas the
predictions of all models agree with the measured cross section in the region
of small E(T,Jet)^2/Q^2, only one model, which includes a resolved photon
component, describes the data over the whole kinematic range.
