This resource explains the Transformation of HeffLocal-HeffNormal (why?), gives a good description of the pluck (e.g. overtone vs. SEP), antagonism between term that lifts degeneracy in polyad vs. term that has off-diagonal intrapolyad matrix elements, 2-level illustration, 3 parameter model ? some inconsistencies, eff6 parameter model Heff Local-Heff Normal.