activator start invocation

[Chad.Davis]

I'm kind of unclear on when and how the BundleActivator.start() method get's 
called.  I understand that when I invoke the bundle.start(), which my app does, 
that the lifecycle method get's called too.  What I'm unclear about are the 
other conditions which would lead to an invocation.  For instance, it seems 
like the container automatically calls it when I restart my application.  Does 
it do that for all bundles in the "running" state?