Moving forward, we suggest that the utility of the TDKS approach for core-level spectroscopy may lie in the fact that it obviates the need to invoke a CVS approximation, which is (by contrast) essential in LR-TDDFT and other eigenvalue-based approaches to x-ray spectroscopy. At the DFT level, TDKS simulations may provide benchmarks to understand the assess the accuracy of activespace approximations, which remain relatively untested for x-ray spectroscopy at element L-and M-edges.