This would allow full path in a way that doesn't require specifying the drive to look at. When this is specified, we will use SYSTEMDRIVE. This would allow multiple computers with different system drives to be able to use the same manifests. This could also open the door for more platforms using the same manifest with less use of selectors based on the OS.
Those would translate to `c:\somepath` and `c:\somepath\somefile.txt` respectively on Windows if SYSTEMDRIVE was C:, otherwise it would translate to whatever the system drive is set to on Windows.