Placing one viewpoint under another in the Viewpoints pane creates a compound viewpoint. That way you can execute combined viewpoints for diagrams and views, for example, a combination of colors and labels.
It is only possible to place viewpoints under each other if the viewpoint overview is in manage mode. A combination of a color view and a label view is shown below.
Compound viewpoint in Viewpoints pane
When the viewpoint overview is in normal mode, only the top-level viewpoints are displayed. When executing a top-level viewpoint, not only this viewpoint is executed, but also any underlying viewpoints, if applicable.
Example of an activated compound viewpoint