Whether a given reference is a facet is subjective, depending on the analysis.
- Where facets come in is during subjective aggregation. When someone, for their own descriptive purposes, aggregates together a subgraph of objects into a conceptual unit, we call such a unit a "composite". We call the entry objects of a composite -- those objects within the composite that may be referred to by objects outside the composite -- "facets". In any object model pure enough to qualify as a capability system, overt (in-model) causality can only enter into a composite from outside via a message to a facet. — (source)