Note: in the solution presented in the class, there was an error: in type "SecType" there was a reference to an element "title". This is not legal, because this element is not a global element, but declared within the element declaration of "report". Only global elements can be referenced.
If we liked to share/reuse the definitions, the best way here might be to define a global named type "Title", and then use this definition in the elements. In the model solution, the definitions are not shared, because they just have the simple built-in type "string".