LMDE - the Xfce variety
LMDE stands for Linux Mint Debian Edition. Xfce, at one time, stood for the XForms Common Environment because the early editions of Xfce used XForms to create a common desktop environment.
The Xfce project originally began around the same time as another desktop environment project, KDE, around 1996. Xfce, in its early implementation, was similar to CDE, the Common Desktop Environment that was prevalent on UNIX workstations in the mid to late nineties. CDE was pretty ugly, and so were the early implementations of Xfce, but arguably Xfce worked better than CDE ever did, and Xfce became portable to a lot more systems.