As an analysis step, often it is desirable to capture simple system requirements. These are eventually realized by Use Cases.
In the initial requirement gathering phase, cataloging requirements can be achieved using the Requirement extension on a Custom diagram.
Requirements can be aggregated to create a hierarchy. The diagram below illustrates how this might be done.
In the following diagram, a requirement that a user can log into a website is implemented by the Login Use Case, which in turn is implemented by the Business Logic, ASP Pages and Login Web Page constructions. Using this approach, you can easily model quite detailed and complex dependencies and implementation relationships.
|•||External requirements can be displayed with or without an identifying E (for External) in the top right corner of the element; to toggle the display of this letter, select or deselect the Show stereotype icon for requirements checkbox on the Options dialog, Objects page|
|•||The colors on Requirement elements identify the status of the requirement; you change the status - and hence color - on the element Properties dialog, and set the color for each status on the Status Types dialog|