With Umsdos, Linux can be installed in a standard DOS partition. Linux is then installed as a second (or third) OS in the partition. To avoid name collision (there is maybe a bin or tmp directory in the drive C: already), Umsdos use a smart trick: The pseudo-root.
All Linux files are installed in a DOS subdirectory
C: LINUX. The normal
Linux/Unix directory structure goes there. So you
When the Umsdos boot, it probes for the directory
/linux/etc. If it exist, it activates
the pseudo-root mode.
Mostly, the pseudo-root mode switch the root of the partition
C:\\LINUX giving the conventional Unix directory
To this list, it adds a new one called
DOS. This one is
a virtual directory.
/mnt, you will find all your linux directory in
/mnt/linux/bin, /mnt/linux/etcand so on.