  The recent enormous improvement of our knowledge of the neutrino oscillation
parameters has motivated us to reinvestigate the allowed ranges of the elements
of the neutrino mass matrix in the basis where the charged-lepton mass mass
matrix is diagonal. Moreover, we have studied the correlations of the elements
of the neutrino mass matrix. The result of this analysis is useful for finding
textures in the neutrino mass matrix and, therefore, for model building in the
lepton sector. As an example, we present two textures of the neutrino mass
matrix which have only two parameters and fit very well all current
experimental data on the neutrino parameters.
