From Xojo Documentation
The full path to the FolderItem using the path format native to the OS.
Applications should not assume that there is a trailing slash on the path returned when the FolderItem is a directory. If the trailing slash is required, the Directory property should be checked and the trailing slash appended based off of that value.
Unlike AbsolutePath, on macOS this returns the POSIX path (separated by slashes).
If the item is a directory (folder), the pathname ends with a backslash on Windows and with a forward slash on Linux.
When accessing a drive on Windows that you do not have permissions for or does not exist, there is no trailing slash. For example, "a:" is a floppy drive with no disk, "a:\" has a disk.
This example displays the native path: