  Radiative transfer out of local thermodynamic equilibrium (LTE) has been
increasingly adressed, mostly numerically, for about six decades now. However
the standard non-LTE problem most often refers to the only deviation of the
distribution of photons from their equilibrium i.e., Planckian, distribution.
Hereafter we revisit after Oxenius (1986) the so-called "full non-LTE" problem,
which considers to couple and therefore to solve self-consistently for
deviations from equilibrium distributions of photons as well as for massive
particles constituting the atmospheric plasma.
