How <Environment Root> Represents the Environment
The feature representation in this example is organized as a <Union Of Features>, where one of the features being organized is a <Point Feature> instance.
Under the "union" organizing principle, a <Union Of Features> is just a "bag" of <Feature> instances.
If all higher-level organization semantics are stripped away, all feature organizations ultimately boil down to <Union Of Features> instances that organize <Primitive Feature> instances.
Similarly, all feature topology organizations ultimately consist of <Union Of Feature Topology> instances.