Requirements in Diagrams

Layer and tools in diagram

Requirements Diagram Example

Requirements and their relations (from/to Capella elements and internal relations between Requirements) can be displayed in your diagrams. For this, the Requirements layer must be activated (activated by default for new diagrams):

Requirements Layer

Once activated, a new segment Requirements appears in the palette tools:

Requirements Segment

In this Requirements segment, 5 new tools are available to manipulate the requirements on a diagram.

Label and content configuration

The label and content displayed for each requirement can be computed dynamically by evaluating two predefined AQL expressions. The two AQL expressions can be configured in the dedicated wizard dialog.

Requirements Configuration Wizard

The wizard can be activated by clicking on the root "System Engineering" of a Capella project which has been referenced by the Requirements Viewpoint.

Menu Item for Requirements Configuration Wizard

By default, there are two predefined AQL expressions for each label and content of requirements. The default length for displaying label and content of each requirement in diagrams are 80 characters. If the result is longer than the preferred length, it will be trimmed and followed by "...". Users have their own rights to define the AQL expressions and the lengths that fulfill their operational needs. However, if the AQL expression is invalid, in other words, could not be interpreted, the result will be displayed as <undefined>.

Special case of displaying requirements in diagrams

The AQL expression is very flexible and easy to use for almost every operational need. For instance, the example below shows how we can display the content of each requirement by aggregating information from 3 properties in 3 bulleted lines:

aql:OrderedSet{self.ReqIFLongName, self.ReqIFChapterName, self.ReqIFText}->select(s | s != 'null' and s.size() > 0).prefix('- ')->sep('\n')


  • After each modification of the AQL expressions, each diagram needs to be refreshed manually by users so that new changes will be taken into account. It is possible to refresh all diagrams at one click by following the screenshot below.

Refresh all diagrams