A model element is an elementary component of a model. It will be created when you create a shape on a diagram. An example of model element is actor.
You can visualize an existing model element or we sometimes call it to ‘reuse’ a model element with the model completion feature. When you create a shape, press Ctrl-Space to popup a list of existing elements. Click on the desired element to reuse it. We call the visualized form of model element a view or a shape, depending on whether we want to emphasis the differences against model element or we want to focus on diagramming operations.
When developing context-based diagrams, you will reuse a model element in different diagrams, resulted in the creation of multiple views. Each model element can associate with zero to multiple views. When you make specification-level change, such as changing of name on any view, the change will be applied to all views.
Showing the other views of a view
If you want to open another view of an existing view (i.e. shape), right click on the view in the diagram and select Related Elements > Show Other Views… from the popup menu. Then, select the view to be opened in the Show View window and click Go to View to open the diagram.