You can annotate entities in any system model that you can see in source cross-reference. In Klocwork Static Code Analysis, you can only add or modify annotations for the System Model as user models are not available.

All users have read/write access to annotations.

Annotations can be useful for several purposes. You can add annotations

to code entities as you learn about the code. These annotations may be useful additions to source code comments.
to code entities to instruct other software developers about required changes, or to inform them about changes you have made or are planning to make
that describe guidelines about system components or refer to external documents such as project plans, presentations and specifications

Tips for adding annotations

In the case where there are multiple entities with the same name, place, and type (for example, multiple constructors or overloaded methods), an annotation added to one of these entities will be attached to all of them.
All characters are acceptable input, but HTML tags are not recognized and will appear only as typed in the annotation.
While it is possible to create lengthy annotations, you may prefer to link to an associated document.