A Requirement element is a type of a constraint that specifies stakeholder-imposed constraint that a design solution must satisfy to be a valid solution. It contains features that are constraint usages called as the required constraints.

Requirement usage is a type of a constraint that is the usage of a requirement definition in some context, which can be provided by a package, part or other requirements. A design solution must satisfy all of its requirements and constraints to be a valid solution.

A Requirement must have a subject which is a parameter that connects the requirement to the model element, such as a part. Requirements can also have Actors and Stakeholder parameters that are parts representing entities that play special roles in relation to the requirement. In SysML 2.0, actors are parameters and not model elements as in SysML1.

Requirements can be resolved to True or False. A requirement is resolved to True when requirement constraints have been met and the requirement has been Satisfied. When a requirement is True, the requirement is deemed satisfied.

To create a Requirement from the System Structure Diagram toolbar:

To create a diagram from the context menu:

You define nested / decomposed requirements within requirements. To define nested requirements, you can drag and drop requirements within existing requirements, create new requirements using the context menu or create new requirements within existing requirements on the diagram itself.

You can link these requirements to other system design elements from traceablity and verification. In Modeler, you can use the following flow types for connectivity with Requirements: