  We present a classification of possible parametrizations of the 3x3 lepton
flavor mixing matrix in terms of the rotation and phase angles. A particular
parametrization, which is most convenient to describe the observables of
neutrino oscillations and that of the neutrinoless double beta decay, is
studied in detail. The possibility to determine the Dirac- and Majorana-type
CP-violating phases are also discussed.
