In Shield Windows client all files and folders on end users' computers will be backed up by default, except System and Program folders and the Windows folder.
In OS X client all files in user's Home Directory will be backed up by default, except Library folder and all it's subfolders (e.g. iCloud Drive). So please note that contents of Library folder cannot be backed up.
Administrators as well as end users themselves can also exclude additional folders and content / file types from the backup (e.g. external drives, compressed files, binaries etc).
End users can do this in their client settings, by selecting Settings. In Exclusions click ...except and in the new popup window tick the content types and formats that should be left out from the backup.
End users can also select individual folder(s) to be excluded from the backup. Click ...except and in the new popup window click Change and Folder (bottom left). You can now see the directory structure of your computer, and you can tick everything that doesn't need to be backed up. Usually contents in the User Folder are the most important ones, e.g. Desktop, Documents etc. Be sure to leave those unticked to back them up.
Administrators on both vendor and company level can change the settings via Nexetic Shield control panel.