Within a folder you can set hierarchies as well. In other words you can change the Sequence of the deposited parts (folder) or make subdirectories for other folders.
Parts dragged and dropped (folders) can either be stored in the main folders (checkin [Check-in] or parts list [Bill of material] ) or as subdirectories for insertion points - e.g. item 3.1 for within the folder item: 3.