Doubt in [Event("XXX")]

Hi,guys. I found some snippets in the Xiff source code such as :

[Event(“outgoingData”)]

class org.jivesoftware.xiff.core.XMPPConnection{

}

That puzzled me . What does [Event(“XXX”)] mean and how it work? Is it like the Annotation of Java?

Or it is only a flakey habbit of ActionScript?

Could somebody help me? thanx a lot.