"Rest Energy" is the energy equivalent of the rest mass of a body, equal to the rest mass multiplied by the speed of light squared.
Applicable units are those of quantitykind:Energy
http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31895
http://en.wikipedia.org/wiki/Invariant_mass#Rest_energy
"Rest Energy" is the energy equivalent of the rest mass of a body, equal to the rest mass multiplied by the speed of light squared.
For a particle, $E_0 = m_0 c_0^2$, where $m_0$ is the rest mass of that particle, and $c_0$ is the speed of light in vacuum.
http://www.iso.org/iso/catalogue_detail?csnumber=31895