Allow expressing that a term can be applied any collection and is not restricted to entity sets

We have a number of annotations (for example, in the capabilities vocabulary) that target entity sets. Most of these annotations can similarly be applied to containment relationships and singletons. How does the service apply such annotations to containment/singletons?

AppliesTo is only a hint, so the Capability annotations can already applied to non-containment navigation properties that are just collections of entities and not entity sets.

Still open: does AppliesTo="EntitySet" imply that the annotation can target any collection of entities, or do we need an additional AppliesTo value, e.g. "Collection"?