A Requirement Diagram (req) is used to graphically depict hierarchies of stakeholder needs, requirements and test cases or to depict an individual need/requirement/test case and its relationship to other model elements. Needs, Requirements, and Test Cases are created and managed in Cradle’s powerful Requirement Management (RM) module and cross referenced to the SysML modelling elements.
As a project may have hundreds of requirements, there is no value-add to placing lots of requirements on a single diagram. Rather requirements tables are usually used to shown large amounts of data. Therefore the req diagram is most often used to show one or more key requirements along with what they were derived from (stakeholder need, use case, or high-level derived requirement) and which design elements will satisfy the requirement.
SymbolsAn example req is:
The symbols available in reqs are:
| Symbol | Name | Description |
|---|---|---|
 | Comment | Makes a note anywhere in the diagram. Are always surrounded by * characters. Note: If you do not want Cradle to automatically add an * go to the Graphics Settings section of Project Setup and turn off the Automatically add asterisks to diagram's comment symbols option. |
 | Picture | Allows you to choose the location of a GIF or JPEG image to be displayed as a diagram symbol. An image can also be embedded in the other diagram symbols. |
 | Note Callout | Multi-purpose symbol which attaches to other symbols in order to show certain attributes of the model element. It can show frames, categories, tags, related items, or simply a piece of standalone text. The following figure shows a Callout that displays a relationship: |
 | Tag | A stereotype can be tagged with additional information/data needed to fully specify the element such as a time, event, constraint, etc. Please note there are currently no Tags defined for the symbols on a Requirements Diagram. |
 | Requirement | This symbol identifies Cradle requirement items that are created outside the SysML model in the Cradle Requirements Management module. These items can be built-in requirement item type or a user-defined requirement item type such as: Stakeholder Requirement, System Requirement or Software Requirement. Please note that these non-model elements (requirements and test cases) are NEVERcreated as a result of being drawn on a diagram. You can also drag and drop requirements from any tree/model browser on to the diagram to create the symbol. When the Requirement symbol is placed on the req diagram the user must choose which type of item and the item's name. The item type and the name of the item are specified using the Name Symbol dialog. The user has the option to display additional symbol compartments using the sidebar checkboxes:  Note: The requirement must exist in the database prior to placing on the diagram. Also, if deleting a Requirement symbol, only the symbol is deleted, i.e. the requirement is not deleted from the database. If you delete the requirement, the symbol is not removed from the diagram. Upon opening or refreshing the diagram requirement names will be updated to match the equivalent items in the database. |
 | Test Case | A Test Case symbol represents a user-defined system note item type that is created outside the SysML model in the Cradle Requirements Management module. For example the following illustrates a Test Case system note item type: You can also drag and drop test cases from any tree/model browser on to the diagram to create the symbol. When the Test Case symbol is placed on the req diagram the user must choose the type of item and the name of the item to be displayed on the diagram using the Name Symbol dialog. The Test Case symbol has optional compartments that can be displayed. See the Compartment checkboxes in the sidebar:  Note: The test case must exist in the database prior to placing on the diagram. Also, if deleting a Test Case symbol, only the symbol is deleted, i.e. the test case is not deleted from the database. If you delete the test case, the symbol is not removed from the diagram. Upon opening or refreshing the diagram test case names will be updated to match the equivalent items in the database. |
 | Constituent | The Constituent path symbol is used to show how a requirement can be partitioned into a set of requirements without adding or changing their meaning. This path is sometimes known as a containment path. In Cradle we use containment to associate elements to a containing package so in this case we are using the phase constituent to name the path. |
 | Dependency | The Dependency path symbol is used to show traceability between elements on the Requirements Diagram. The following dependency relationships can be drawn on the req diagram:
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 | Non-Requirement Element | A SysML modelling element is placed on the diagram in order to graphically show traceability to stakeholder needs, requirements and test cases. See the Dependency path symbol for relationships that can be drawn on a req diagram. |
The symbols along with their default stereotypes, referenced elements, stereotype frames and cross reference link attributes are:
| Symbol | Name | Default Stereotype | Referenced Element | Stereotype Frames or Cross Reference Link Attributes |
|---|---|---|---|---|
| Comment | None | None | None |
| Picture | None | None | None |
| Note Callout | None | None | None |
| Tag | None | None | None |
| Requirement | Non-Modelling Cradle item type | None | None |
| Need | Non-Modelling Cradle item type | None | None |
 | Package | None | None | None |
| Test Case | None | None | None |
| Constituent | None | None | None |
| Dependency | None | None | None |
| Non-Requirement Element | Any SysML stereotype | None | None |