also important. We have found that the contribution from all $d$ orbitals of the core to the valence shifts for Cs gives a value that is less than $10^{-4}$ times the size of the shifts from the core $s$ levels; that is, [*$d$ level valence Uehling shifts are completely determined by the Uehling corrections to the $s$ and $p$ orbitals of the core*]{}.

Of the core $s$ levels, the uppermost core $s$ orbital ($5s$ for Cs) gives the largest contribution, many times larger than the contribution from $1s$.

This consideration is of significance for the problem of the radiative potentials for use in many-electron atoms, where fitting factors are found by reproducing self-energy shifts in hydrogen-like ions. To good accuracy, radiative potentials need only be fitted to $s$ and $p$ self-energy shifts in hydrogen-like ions; it is not necessary to fit to $d$ shifts. Also, it is more important to optimize the fits for the higher, rather than the lower, core $s$ levels.

Due to the presence of $s$ electrons in the core, one may expect that QED radiative shifts for $d$-levels for highly-charged ions are also determined largely from core relaxation effects. This may change the magnitude and sign 