JFred ruleset langauge has remained pretty much the same since Paco Nathan designed it in 1997 or so. However, some of its capabilities have been updated since then.
JRL is a scripting language for the JFRED bot, usually a java application but sometimes an applet. JRL tags for setvar and equals have been improved since the program's inception by some open source contribitions and by the hand of Robby Garner. For the bot, this means that variables can be set during a conversation with no relation to the grammar being used, and action rules may be executed conditionally based on the value of variables set elsewhere in the conversation. These are powerful features that make the JRL bot useful and scriptable.
Paco set most of these functions in place originally, but they are only recently being reclaimed as updates to the jfred library have been made. The Institute of Mimetic Sciences has been keeper of this code for some time, and is working to improve the code beyond its humble ambitions initially set forth by Paco and Robby.