  We investigate a specific set of two-loop self-energy corrections involving
squared decay rates and point out that their interpretation is highly
problematic. The corrections cannot be interpreted as radiative energy shifts
in the usual sense. Some of the problematic corrections find a natural
interpretation as radiative nonresonant corrections to the natural line shape.
They cannot uniquely be associated with one and only one atomic level. While
the problematic corrections are rather tiny when expressed in units of
frequency (a few Hertz for hydrogenic P levels) and do not affect the
reliability of quantum electrodynamics at the current level of experimental
accuracy, they may be of importance for future experiments. The problems are
connected with the limitations of the so-called asymptotic-state approximation
which means that atomic in- and out-states in the S-matrix are assumed to have
an infinite lifetime.
