For a `gaussianRing` R generated with a digraph and an instance of the type Bigraph the class we retrieve when typing R.graph is MixedGraph. This is consistent with the treatment of such objects. Therefore, this variable is essentially used to differentiate graphs from a graph and an instance of the type MixedGraph.

- gaussianRing -- ring of Gaussian correlations on n random variables or a graphical model
- gaussianRingData -- hash table with main parameters of a gaussian ring