Clicking the plus sign instead of double clicking the model allows you to browse the model without opening the diagram, and thus potentially triggering other models to load.
After a Browse Diagram with a chosen focal element has rendered, you can then double-click on any of the related elements to create another Browse Diagram that has that element as the focal element.
A stereotype allows you to attach a new meaning to a UMl foundation class, such as class, and it is represented on a UMl diagram as a name surrounded by double brackets .