The "Relative Mass Defect" is the mass defect between the monoisotopic mass of an element and the mass of its A + 1 or its A + 2 isotopic cluster.
Applicable units are those of quantitykind:DimensionlessRatio
http://en.wikipedia.org/wiki/Binding_energy
The "Relative Mass Defect" is the mass defect between the monoisotopic mass of an element and the mass of its A + 1 or its A + 2 isotopic cluster.
$B_r = \frac{B}{m_u}$, where $B$ is the mass defect and $m_u$ is the unified atomic mass constant.
http://www.iso.org/iso/catalogue_detail?csnumber=31895