Assosiasjoner på datatype
Requirement 12. Data types, which lack identity, shall be used only in attributes and strong aggregations (composition).
Requirement 13. A data type shall only have an outward pointing association if one of the following is true:
1)The target of the association is another data type and the association is a composition
2)The target of the association is a well-known immutable object for which a universally recognized identifier exists.