  State space and entropy rate of a discrete non-equilibrium system are shortly
considered including internal variables and the contact temperature. The
concept of internal variables in the context of non-equilibrium thermodynamics
of a closed discrete system is discussed. The difference between internal
variables and degrees of freedom are repeated, and different types of their
evolution equations are mentioned in connection with G\'{e}rard A. Maugin's
numerous papers on applications of internal variables. The non-equilibrium
contact temperature is recognized as an internal variable and its evolution
equation is presented.
