Figure 2: Schematic diagramm of ν masses, i.e. of the eigenvalues of the ν mass eigenstates: The 4 schemes show allowed distributions of the three mass eigenvalues with the differences Δm2ij given by experimental evidences from experiments on solar and atmospheric neutrinos. Note that no absolute scale of the neutrino masses is shown. Neutrino oscillation evidences lead to mass differences and a lower mass limit, but donot determine absolute mass values.