  The physics content of the QGSJET-III Monte Carlo generator of high energy
hadronic collisions is discussed. New theoretical approaches implemented in
QGSJET-III are addressed in some detail and a comparison to alternative
treatments of other cosmic ray interaction models is performed. Calculated
characteristics of cosmic ray-induced extensive air showers are presented and
differences between the respective results of QGSJET-III and other models are
analyzed. In particular, it is demonstrated that those differences are partly
caused by severe deficiencies of the other interaction models.
