Feature Topology
A <Feature> represents something in the environment so as to abstract away any spatial information that isn't needed to reason about that "thing" in terms of its spatial connectivity.
A <Feature> does not directly contain spatial information; instead, it is associated with some <Feature Topology> organization.
The topology of a <Feature> contains the spatial data and further information about its connectivity with other data, while the <Feature> itself supplies such things as <Classification Data> and <Property Value> instances that apply to the entire "thing".