By encoding fully nonlocal information through N e ([ρ]; r, x), MRF has a range of advantages missed by standard functional. It is free of one-electron self-interaction error, it captures electronic correlation arising upon bonds stretching in a seamless manner, and provides correlation energy densities within the standard DFT definition (i.e. gauge) that are fully compatible with the exact exchange energy densities . These good features of MRF arise already by its construction, and thus, provide a different starting point for building a new class of the XC functional approximations that overcome the drawbacks of current ones.