  The parton distributions functions (PDFs) derived from the NNLO QCD analysis
of existing light-targets deep-inelastic-scattering data are presented. The NLO
and NNLO PDFs are compared in order to analyze perturbative stability of the
analysis and estimate impact of the higher-order QCD corrections. The main
theoretical uncertainties and experimental uncertainties in PDFs due to all
sources of experimental errors in data are estimated and used to assess
corresponding uncertainties in the cross sections of other hadronic processes.
