  We parameterize the second post-Newtonian (2PN) metric for a gravitating
system of fluids in the generalized harmonic gauge, and find that there are
only three independent 2PN parameters (i.e. $\omega$, $\delta$ and $\delta_2$)
for satisfying some conservation laws including the conservations of energy,
momentum, angular-momentum and the uniform motion of the center-of-mass.
