  We show a general kinetic equality for susceptibilities (KSE) of general
fluctuating quantities and for the dynamical activity of nonequilibrium systems
described by Markovian master equations. As special limiting cases, KSE
reproduces the so-called kinetic uncertainty relation and its multivariate
extension. To derive KSE, we also show a kinetic generalization of fluctuation
theorem, and an equality for the susceptibility and the observable-frenetic
covariance. Hence, KSE provides a master relation of these nonequilibrium
kinetic relations.
