// assuming there is only one module defined:Index
Request: http://yourdomain.com/a/b
=> module = index, controller=a, action=b

//assuming ap.action_prefer = On
Request: http://yourdomain.com/b
=> module = default(index), controller = default(index), action = b

//assuming ap.action_prefer = Off
Request: http://yourdomain.com/b
=> module = default(index), controller = b, action = default(index)


Request: http://yourdomain.com/a/b/foo/bar/test/a/id/4
=> module = default(index), controller = a, action = b, request parameters: foo = bar, test = a, id = 4