The meaning of the reaction anharmonicity curves A and the bond contributions thereto in Fig. is less intricate than of the force constants in Fig. . High values of this parameter are convincingly associated with the running process of bond alternation in a system. It may be bond rupture (negative values) or bond creation (positive values). Significant values of the bond components reported in Fig. are only fewapparently, the reaction is dominated by the N1-H4 bond breaking and O3-H4 bond creation. All noticeable contributions from bonds to A involve the links of H4 atom with all but the isolated H6 atom. The role H5-H4 contact, though marginal in this process, confirms the role of protons, being potential sensors for the electronic process nearby.