“…During this qualification, described in detail in Appendix E, (a) the energy levels are equipped with uncertainties, dependability grades, and useful connectivity parameters, (b) the transitions are rated using the grades of their upper and lower energy levels, and (c) segments are associated with statistical data concerning their wavenumber ranges and their accuracy. 45,46,62,[98][99][100][101][102] Note that a complete update of the IUPAC Part III paper 17 is in progress. 107 In Table 2 segments of experimental sources, old and new, are collected reporting highly accurate measured transitions, defined as having ESU ≤ 10 −4 cm −1 .…”