  High-energy factorization in QCD is investigated beyond leading order and its
relationship to the factorization theorem of mass singularities is established
to any collinear accuracy. Flavour non-singlet observables are shown to be
regular at small x order by order in perturbation theory. In the singlet
sector, we derive the relevant master equations for the space-like evolution of
gluons and quarks. Their solution enables us to sum next-to-leading corrections
to the small-x behaviour of quark anomalous dimensions and deep inelastic
scattering coefficient functions. We present results in both MSbar and DIS
factorization schemes.
