EJB3 + JEE6: What is a persistent Timer?

I'm just about to use the new EJB3 TimerService (as part of Java EE 6), and as usual, I'm impressed by the brevity of JavaDoc :)

Do you know what is the effect of the persistent property of the TimerConfig object?

JavaDoc TimerConfig says: The persistent property determines whether the corresponding timer has a lifetime that spans the JVM in which it was created. It is optional and defaults to true.