The System: drive is for your for system settings and your software catalog. It is read only, you cannot write to the System: drive, and there will be no “+” icon here to create new directories or sub-folders. You will still, of course, be able to “Search”.
You can change your settings, view documentation, find available software or tools from here. Like the Home: disk, the window position is remembered.
In here the following folders will be found:
Devices
Documentation
Functions
Libraries
Modules
Repositories
Settings – Settings apps like customization /editing various items
Software – all the applications installed on your Friend account