| CountCache | This class handles the count cache for the folder structure. |
| CustomField | This class handles all hooks for the custom field in a attachments dialog. |
| Filter | This class handles all hooks for the general filters. |
| Permissions | Folders permission handling. |
| Shortcut | Handle the metadata and attached file for shortcuts. |
| Structure | This class handles all hooks and functions for the structure. |
| Upload | Handling uploader, so files can be uploaded directly to a folder. |