Based on the above results, we suggest that MMBs in PCMs and the Ah and Ai phases of group-15 and -16 elements are equivalent to the EDMBs in boranes and also similar to those occurring in elemental nitrogen and hydrogen at HP once intermolecular and intramolecular bonds equalize . Therefore, as previously mentioned for MMBs, the EDMB formation at HP in different elements, such as H, N, As, and Se, is characterized by a coexistence of localized and delocalized electrons and is an intermediate step between covalent bonding, with fully localized electrons, and metallic bonding, with fully delocalized electrons. This view is consistent with the progressive delocalization of electrons as pressure increases until the metallic bond is reached at enough HP . In this context, we consider that negative values of ICOBI(3c) found for MMBs in PCMs and group-15 and -16 elements, which have been interpreted as indicative of ERMBs, could have been misinterpreted and should be thoroughly revised. Note that the negative values of ICOBI(3c) found in MMBs are close to zero, i.e. smaller in absolute value than those reported in molecules with ERMBs, like XeF2 . It is also important to stress that our results, which consider that MMBs in PCMs and in the Ah and Ai phases of group-15 and -16 elements are equivalent to EDMBs in boranes and also in the polymeric HP phases of nitrogen and hydrogen, are in contradiction with previous assumptions that suggested that ERMBs should occur at HP for elements of groups 14-18 of the periodic table since typical hypervalent molecules with this kind of bond, such as I3 ꟷ , XeF2, XeF4, and XeF6 , correspond to elements of these groups. Note that the EDMB formation was previously assumed to occur for elements of groups 1, 2, and 13 since they are present in typical molecules with this kind of bond, such as H3 ꟷ , B2H6, and Al2H7 ꟷ .