Er, What's DF0:?
But that is precisely the difference between the Microsoft concept and the sane world. How could they name their devices A,B,C, ... without ever thiniking about the future. How can an OS that is new in 2009 (Windows 7) still have C: as the hard wired name for the primary partition? At work we have trouble because UNC-paths aren´t universally supported and with only 26 letters in the alphabeth there is some double usage of the same letter.
In the Unix- and the Amiga-scheme you will never run out of device names. You can extend the scheme to accomodate for new developments, without breaking exisiting software and without looking goofy.
We knew that in 1988, but Microsoft didn´t care and they never did the right thing and thow it out of the Windows (pun intended). So we are old, but Microsoft is old and stupid.