The Common Desktop Environment (CDE) is a free desktop environment for Unix and OpenVMS, based on the Motif widget toolkit.
Ranked in these QuestionsQuestion Ranking
Pro Useful for low-end devices
As Linux moves into low-end territory with the likes of Raspberry PI, CDE's level of consumption seems extremely small. When it was first developed, 128MB or RAM was a lot.
CDE was developed more than 20 years ago to work as a unified DE for all the various forms of commercial, proprietary Unix operating systems that dominated the market back then: AIX, TRU64, HP-UX, Solaris, IRIX etc...
Nowadays it's released as an open source Desktop Environment for Linux. It comes as a free tested, widely deployed and enterprise-level product even if it's recently re-release as FOSS for Linux.
Con Outdated UI
The graphical interface is very outdated and ugly. It's mostly for lower-end machines and for people who want to give their Linux machine a true UNIX feel.