Hierarchy of objects
The folder 'Objects' contains the hierarchy of statistical objects that can be selected
The icon can indicate an object 'parent' to other more specific object, an object with no children or a container of other objects. In the first case the object is selectable, as its children object, by just clicking with the mouse; in the third case only the objects contained are selectable. Of course, an object with no children is selectable too.
Clicking on the icon the children of a generic object or of a container can be viewed; they can be in their turn objects or containers.