From [1]:
The X11 Conservancy Project (X11CP) pulls together the disparate set of programs which
were being written between the very late 80s, and early 90s -- usually for Unix and
Linux.
…snip…
As the Internet expanded and Linux distributions became established, certain FTP sites
were largely used to host some of the more established programs, as well as those found in
the LSM.
…snip…
But the early dawn of free software, especially around applications written for X11, using
Motif and XT and other widget libraries has now mostly been consigned to obscurity.
With X11 itself now under threat of no longer being developed in favour of Wayland, these
applications are going to be harder to run and be discovered.
Hence, the X11CP is designed to be a central place for hosting the sources of these
applications, and to showcase their unique history and properties. In keeping this
software active, it will help keep an important historical point alive.
[1]
https://x11cp.org/
— Michelangelo