  For a system in contact with several reservoirs $r$ at different
inverse-temperatures $\beta_r$, we describe how the Markov jump dynamics with
the generalized detailed balance condition can be analyzed via a statistical
physics approach of dynamical trajectories $[{\cal C}(t)]_{0 \leq t \leq T} $
over a long time interval $T \to + \infty$. The relevant intensive variables
are the time-empirical density $\rho(\cal C)$, that measures the fractions of
time spent in the various configurations ${\cal C}$, and the time-empirical
jump densities $k_r ({\cal C', \cal C}) $, that measure the frequencies of
jumps from configuration ${\cal C} $ to configuration ${\cal C '} $ when it is
the reservoir $r$ that furnishes or absorbs the corresponding energy difference
($E({\cal C '})- E({\cal C })$).
