With the expert comment you can present expert knpwledge that exceeds
This can be extensive knowledge as well as basic knowledge.
It would overload the information text or answer comment if too much expert information was presented there. And this also helps to ensure the continuity of the story board.
For the formulation of the expert comment the same princples of conciseness, understandability and clearness are relevant, as it is described in chapter “text design”.
It is reasonable to give a hint on the expert comment when a screen card contains one. E.g. “Please also see the expert comment for further information concerning […].”