Comments
From the SysML 2.0 specification, a comment is a kind of an annotating element that is used to provide textual descriptions about other elements.
Creating a Comment
To create a comment:
1. On the System Structure Diagram toolbar, click the Comment 
button.
button.2. On the diagram, click on the canvas. This creates a Comment. You can use the Annotation Link to connect the comment with the related item.