Energy and proper time (not relativity)

Hi guys,

In a scientific paper, I have found the following sentence:

"...given the fact that the system is homogeneous in energy, or equivalently, that it has no proper time scale."

I'm not sure about what the authors intend to say (what is the relation between being homogeneous in energy and having (or not) a proper time scale). I know the relationship of energy and time as conjugate variables in the formalism of quantum mechanics but this paper is about linear thermodynamics.

Perhaps you interpret this better than me.

Thanks in advance