THE OPM User's Guide has some information; search on the word "event" or "rule loop".
There is a section in the user guide called "Use rules to trigger external software applications" that mentions custom event rule and raiseevent.
There is another section called 'Model Loops in Rule Logic".
Edited by: 941611 on Jan 17, 2013 7:25 AM
I find the Developer Guide more in depth, but truly is a challenge to connect topics to get all the pieces of knowledge.
There is a section on Events and Event Handlers in the OPM Developer's guide that is more than a few lines.