Before revision:  This justification is not only of theoretical relevance, but leads to many insights that are of direct practical use: the reference state is uniquely defined by the probability distributions involved, PMFs can be generalized beyond pairwise interactions to arbitrary features of protein structure  and it becomes clear for which purposes the use of these potentials is justified.
After revision:  We call these quantities reference ratio distributions deriving from the application of the reference ratio method. This new view is not only of theoretical relevance, but leads to many insights that are of direct practical use: the reference state is uniquely defined by the probability distributions involved, PMFs can be generalized beyond pairwise interactions to arbitrary features of protein structure and it becomes clear for which purposes the use of these potentials is justified.