Assemblies often contain many items and sub-assemblies. You can group an assembly so that when you click any of its sub-components in the 3D view, it selects the grouped assembly. This makes it easier to select the correct item in the 3D view and perform operations on it.
The
icon is displayed in the Project Tree beside grouped assemblies. When a top level assembly is grouped, the group icons of its sub-assemblies are unavailable. You can still click the greyed-out icons to group or ungroup items that are nested within parent groups.
The
icon is displayed in the Project Tree beside ungrouped assemblies.
Note: The availability of this feature is license dependent.