For both pointwise and polynomial featurization in Figure , the most informative parts of the spectra shift from the pre-edge region to other regions of the spectrum when moving from lighter to heavier 3d metals. The importance of the post-edge region accords with prior work , but our polynomial featurization provides the additional insight that coordination is largely determined by the constant terms of the polynomial in that region, indicating that the magnitude of the spectra is more important than local linear or quadratic behavior.