I assume its numerical order for the banners. I was showing 20 banners, I turned one on to see what number it was and id=33. I did have all options being displayed by adding new banners. I would need to turn them all back on to determine which was in the 16 slot.
It does not matter which slot I add new banner to. everything from overall all the way down. firefox just does not take it. When the page comes up and says
If you page does not show shortly, please click Here to go to the requested URL
I can click the "here" link and it will take me to the designated site.
EDIT: I just checked my ver of fox and it says no new updates for version 3.0.3