[rules-users] Question about signalEvent method

Alright, I feel dumb posting this question, but I can't seem to find an answer anywhere. When I use signalEvent, I know I'm passing it the event I want to fire, but then there is the "Object event" parameter. What exactly happens if I fill this parameter? What I'd like to do is the following: Get a running process id, and signal an event on the process -- in my case "AttachAudio". However, the AttachAudio is going to be proceeded by an action, which will be responsible for actually attaching my audio object to a running Alert in my system. So, obviously I need to inject the audio object into my process instance. Is that what the "event" parameter does on signalEvent? And if so, how does it know what variable to inject the object into? If not, how can I do something like processInstance.setVariable ("audio",audioObject); processInstance.signalEvent ("AttachAudio",null); ? Thanks for your help in advance. Dan Miller