I have found the following page:

http://minnow.cc.gatech.edu/squeak/716

useful. However at the bottom of it is broken link.
Don't you know where it should point to? I was not
able to find any Self site which would explain those
messages in the original environment.
-- 
Matej Kosik <http://infobox.sk/kosik>
ICQ: 300133844