A quantum-theoretic formulation of the FEP (qFEP) was introduced in [1]; see [2] for a comparison of the classical and quantum formulations and [3–6] for applications of qFEP to generic systems. The fundamental distinction between the classical FEP and qFEP is in the representation of information flows between systems; these are continuous in the classical FEP and discrete in qFEP. Hence the classical FEP can be seen as the classical “macroscopic” limit of qFEP, the limit in which information flows are large enough to be considered continuous.