NIST’s fork of CDE, a lightweight virtualization method for Linux programs. The original sadly doesn’t seem to be online anymore.
CDE packages Linux programs along with a copy of the operating system’s loader (ld.so) and all the libraries and files they open when you run it once. You can also copy more files into it if you know that you will need them. The resulting packages can be run on most Linux systems independent from the host system’s loader and library versions.