M^B_L \partial^A_L
|z_A - z_B|^{-1}$\].

In the monopole (LD-EIH) or pole-dipole limit Eq. (\[twelve\]) yields the well-known result that the total mass-energy is the sum of the total rest-mass and the kinetic and potential ($\propto GM^AM^B/|z_A-z_B|$) energy terms. Let us recall that, in the general case, the individual post-Newtonian gravitational masses $M^A$ are no longer constant (because of tidal forces acting on the extended bodies, see Eqs. (4.20a) and (4.21a) of [@dam2]) and that it is not a priori evident that the quantities $m(t)$ or $m^{\rm
standard}(t)$ are conserved. As a check on our algebra, we have verified by a direct calculation that this is indeed the case.

As an aside, let us conclude this sub-section by noting that if one defines, as an auxiliary technical quantity, the “Fock mass” of the $A$-th body by the relation $c^2 M^A_F =
\int_A d^3X_A\, (1+W/2c^2) {\bf T}^{00}_A$ (where ${\bf T}^{00}_A$ denote the $X_A^0$-$X_A^0$ component of the stress-energy tensor considered in the local coordinate system $X_A^\alpha$), one can write our result (\[twelve\]) in a formally compact (and familiar looking) form. The name we give to this quantity is based on the fact that in his book [@fo] Fock used such an expression for 