As elaborated in Ref. 2, the quantity d e-h is essentially the same as a metric called "D CT ", which is widely used to analyze TD-DFT calculations but was introduced in a manner that obscures its connection to the particle and hole density matrices. As such, we prefer the straightforward definition in eq. 15 and the intuitive nomenclature of "d e-h ". More complicated extensions of D CT have been suggested, though the need for them is unclear to us.