  Four zero neutrino Yukawa textures in a specified weak basis, combined with
$\mu\tau$ symmetry and type-I seesaw, yield a highly constrained and predictive
scheme. Two alternately viable $3\times3$ light neutrino Majorana mass matrices
$m_{\nu A}/m_{\nu B}$ result with inverted/normal mass ordering. Neutrino
masses, Majorana in character and predicted within definite ranges with
laboratory and cosmological inputs, will have their sum probed cosmologically.
The rate for $0\nu\beta\beta$ decay, though generally below the reach of
planned experiments, could approach it in some parameter region. Departure from
$\mu\tau$ symmetry due to RG evolution from a high scale and consequent CP
violation, with a Jarlskog invariant whose magnitude could almost reach
$6\times 10^{-3}$, are explored.
