What is your specific question? If you want to declare the Notification datatype just select it as the datatype from the development environment in the C/AL locals or globals window.
But I can not find the Notification datatype from the development environment in the C/AL locals or globals window. It makes me confuse why the Notification not in the Data Type column.
Answers
But I can not find the Notification datatype from the development environment in the C/AL locals or globals window. It makes me confuse why the Notification not in the Data Type column.
The Notification Data type is form NAV 2017.
https://community.dynamics.com/nav/b/richardrobbersenav/posts/nav2017-notifications-part-1-create-a-simple-notification