  Linear response analysis in the nonequilibrium steady state (Gaussian regime)
provides two independent fluctuation-response relations. One, in the form of
the symmetric matrix, manifests the departure from the equilibrium formula
through the quantity so-called {\it irreversible circulation}. The other, in
the anti-symmetric form, connects the asymmetries in the fluctuation and the
response function. These formulas represent characteristic features of
fluctuations far from equilibrium, which have no counterparts in thermal
equilibrium.
