  Using information theory we derive a thermodynamics for systems evolving
under a collective motion, i.e. under a time-odd constraint. An illustration
within the Lattice gas Model is given for two model cases: a collision between
two complex particles leading to a incomplete relaxation of the incoming
momentum, and a self-similar expansion. A semi-quantitative connection with the
determination of thermodynamical quantities in multifragmentation reactions is
done showing that they are affected in a sizeable way only when the flow
dominates the global energetic.
