  The basic characteristics used for the description of both Dirac and Majorana
massive neutrinos are studied. Currently available experimental data for these
characteristics are presented with an evidence of possible anomalies beyond the
Standard Model with three light neutrinos. Special attention has been paid to
ways to determine the neutrino mass absolute scale. In accordance with the
available data, the permissible values of the neutrino mass matrix elements are
found numerically against the minimal mass of neutrino. Some phenomenological
relations for the masses, the angles and the CP-violating phases of the
neutrino mixing matrix are discussed, and the values of the neutrino mass
characteristics and the Dirac CP-violating phase are evaluated for a model of
bimodal neutrinos. The estimations made for masses of sterile neutrinos, the
values of the neutrino mass characteristics and the Dirac CP-violating phase
can be used for interpretation and prediction of the results of various
neutrino experiments.
