You can create requirements links to and from Simulink.Annotation objects using the Requirements Management Interface (RMI). Annotations are free-floating text boxes that you can place inside a Simulink® model. For more information, see Annotations in the Simulink documentation. You can use RMI linking to associate annotations with other Simulink objects or external requirements documents. Note that requirements linking for annotations is not supported in Stateflow®.
Requirements linking for Simulink annotations is enabled only if you configure your model to store requirements data externally. To specify external storage of requirements data for a model, in the Requirements Settings dialog box under Storage > Default storage location for requirements links data, select Store externally (in a separate *.req file). If you have an existing model that contains internally stored requirements links, you must convert the model to store requirements data externally before you can use requirements linking for annotations in the model. To switch the model from internal to external RMI storage, move all existing requirements links in it to an external .req file by selecting Analysis > Requirements Traceability > Move to File. For more information on requirements links storage, see Specify Storage for Requirements Links.
Note: If you later change your model to store requirements links internally as described in Move Externally Stored Requirements Links to the Model File, or if you save the model in a version of MATLAB® prior to R2012b, annotation requirements links are either discarded or attached to a corresponding parent diagram.
Annotations are context-specific. Unlike copying other Simulink objects, copying an annotation does not copy its associated requirements links. Requirements links from annotations do not appear in generated code, but requirements links to annotations from other Simulink objects do appear.