Mass Independent Textures and Symmetry
  A mass-independent texture is a set of linear relations of the fermion mass-matrix elements which imposes no constraint on the fermionic masses nor the Majorana phases. Magic and 2-3 symmetries are examples. We discuss the general construction and the properties of these textures, as well as their relation to the quark and neutrino mixing matrices. Such a texture may be regarded as a symmetry, whose unitary generators of the symmetry group can be explicitly constructed. In particular, the symmetries connected with the tri-bimaximal neutrino mixing matrix are discussed, together with the physical consequence of breaking one symmetry but preserving another. 
C.S. Lam