CODE4 is a knowledge acquisition and representation tool. It is still being used, but has not seen any new development since 1994 since its researchers have been focusing on other things. Doug Skuce is still actively working in the knowledge management area, and Tim Lethbridge maintains an interest (he still has ideas that he would like to research at some point)
Here's most of the message we send to people who request a copy of CODE4
The following are several places where you can find information about it:
Last Updated Jan, 1996
tcl@csi.uottawa.ca