A direct association extends the domain element and creates a one-to-one, exclusive relationship between the domain element and the requirement. For example, in the UML domain, use-case model elements are directly associated with requirements by default. This direct link further defines the use-case requirement by displaying the model element's interaction with actors and other model elements. It also helps you ensure that your model satisfies all the use cases that are defined in the project requirements. With associated use cases, you can also navigate to documents that elaborate the use cases with descriptions, flows of events, special requirements, and conditions.
By default, use cases are the only domain elements that are configured to directly link to a requirement; however, you can use the Link Policy page of the Project Properties window to configure other requirement types and elements in any domain for direct linking. You can also customize the settings on the Synchronization page of the Project Properties window.
The following figure provides an example of a direct association in the UML domain. The direct link is represented by a link arrow which is visible in both the Project Explorer and Requirement Explorer views. Direct associations behave the same way in any domain with direct linking policies.
When you link domain elements and requirements in a direct association,
the name and text of the requirement is synchronized with the name
and documentation text of the domain element, if you use the default
project properties. If the name and text of the requirement and the
domain element do not match when you create the link, then you are
prompted to resolve any differences between them. This prompt is also
displayed if you change the name or text of either of the linked
artifacts. Synchronization is not required for blank requirement names,
because requirements created within Rational® RequisitePro® documents use the text rather than the name field.