UML 2.0: who owns properties

In UML 2.0 properties can be owned by ether a class or an association.

In case the property is owned by a class it is called attribute i.e. attribute is a role a property can take. There are two notations for attributes:

1. as attribute inside a class
2. as assiociation end (at the navigable end). The role name is the name of the attribute

Both notations are equivalent.

In case an association has an association end that is not navigable the property is not owned by the class at the association end but the association itself.

The navigability of an association end therefore detirmins the ownership of the property:

navigable	property is owned by the class at opposite end (attribute)
not navigable	property is owned by assiciation