Starting with version 2.5.0 you can add a little JavaScript code to your field. With it, you can add a little dynamics to your messages. For example, when creating a issue, display a message depending on the selected fields.
Code examples can be viewed at the link
The code can only be run on selected contexts (create, view, ...) or specify them in the code. If the code has no context, then it will not be called.
In the code from the link above there is an example of how to hide, show and change the message depending on other fields (select).
