Organizing references in a hierarchy.

I see that EndNote supports multiple “Group Sets” and that these can contain “Groups.” Together these allow for a 2-level hierarchy (Level 1 = Group Sets, Level 2 = Groups). Is it possible to create a hierarchical organization of groups within groups such that references can be organized into 3 or more levels?

Test System: Thomson Reuters EndNote X5.0.1 (Bld 5774), Microsoft Windows 7 Enterprise 32-bit.

Have you seen this threadon the topic of organizing groups/group sets?

Thanks for the reference to the pre-existing thread.