  Accurate atomic data have become available in the recent past due to the
demands of astrophysics and fusion research. We report on the impact of such
data on non-LTE line-formation calculations for CNO in early-type stars.
Considerable improvement is achieved by the derivation of consistent results
from practically all available spectroscopic indicators, regardless of
ionization stage or spin system, and the uncertainties in the analyses are
drastically reduced. Moreover, systematic trends are revealed, e.g. an increase
of the NI abundances from previous studies of BA-type supergiants by a factor
of two is indicated. The present work promises stringent observational
constraints on chemical mixing in the course of massive star evolution. First
results on BA-type supergiants in the Galaxy and the Magellanic Clouds are
discussed.
