Going beyond the relatively simple AB2C2 spin system discussed above (Figure ), this study also gathers experimental evidence to explain why and how precise and coherent terminology is crucial to the interpretation of NMR spectra. For this purpose, the following section re-visits αsantonin, strychnine, and testosterone as cases of classical NMR standard molecules and demonstrates the use of the terminology in the specific context of select 1 H resonances of these molecules. In order to provide clear rationales for the terminology, in-depth evaluations of their spin systems are presented and include the establishment of fully QM-based interpretations of the HNMR spectra of these molecules. To expand the picture for broader adoption, the following also reviews a portfolio of already reported cases that cover the entire range of small molecules. spin systems. These patterns can only be understood by knowing the actual underlying spin systems, and by taking into account the relations between the five lines that give rise to the four readily visible peaks. Spin A * of the more abundant AB2C2 component gives rise to a triplet pattern with a slight 'roof effect', where line 1 intensity is slightly less than 1, and line 3 intensity is slightly greater than 1. Spin A # of the less abundant ABC3 system appears as a doublet that also slightly leans to the right. Such minor deviations from the first-order multiplicity rules are often referred to as 'higher-order' effects and are very common, even in spectra acquired at ultra-high magnetic fields. Higher-order effects occur when the Larmor frequencies of two coupled nuclei are not significantly greater than their J-coupling value. These deviations also mean that the intensity ratios in the signals of the coupled nuclei do not exactly match the theoretical values of 1:2:1 in the triplet and 1:1 in in the doublet. In fact, deviations are often substantial. This already exemplifies one main challenge of integration-based qNMR (int-qNMR): unless pure first-order multiplicities are achieved, the dissection of the intensities of overlapping resonances is hampered or even impossible.