To create a new user message, click 
to the right of the component selected under Analysis Toolchain. The User Messages Dialog will be displayed.
Scroll all the way down to User Specified and right-click on either User Specified itself, or the required component beneath it, and select New User Message. Then enter a Message ID in the range 6000-9999, enter the associated text, followed by the appropriate Severity (0-9) (refer to Viewing and Filtering the Diagnostics). You can also, if required, link the message to an HTML Help File and enter any Reference(s).
Click Create.
To use a newly defined user message with a rule, then, once you have saved the configuration, proceed as in Messages.