UMLR — How is an attribute that is not a part, a role?

11.2.3. says

Property is a kind of ConnectableElement. All of the ownedAttributes of a StructuredClassifier are roles and can be connected using Connectors.

Those ownedAttributes of a StructuredClassifier that have isComposite = true (see 9.5.3) are called its parts. Hence parts constitute a subset of roles

So how are non composite properties (attributes) roles?

A justification, example, and/or an excuse is needed.