  Several parametrizations for overshooting in 1D stellar evolution
calculations coexist in the literature. These parametrizations are used
somewhat arbitrarily in stellar evolution codes, based on what works best for a
given problem, or even for historical reasons related to the development of
each code. We bring attention to the fact that these different parametrizations
correspond to different physical regimes of overshooting, depending whether the
effects of radiation are dominant, marginal, or negligible. Our analysis is
based on previously published theoretical results, as well as multidimensional
hydrodynamical simulations of stellar convection where the interaction between
the convective region and a stably-stratified region is observed. Although the
underlying hydrodynamical processes are the same, the outcome of the
overshooting process is profoundly affected by radiative effects. Using a
simple picture of the scales involved in the overshooting process, we show how
three regimes are obtained, depending on the importance of radiative effects.
These three regimes correspond to the different behaviors observed in
hydrodynamical simulations so far, and to the three types of parametrizations
used in 1D codes. We suggest that the existing parametrizations for
overshooting should coexist in 1D stellar evolution codes, and should be
applied consistently at convective boundaries depending on the local physical
conditions.
