I posted this on SW too since I know that Mitel and PBX people who support Mitel are much more common over there.
I received the following response from Eric from Mitel
The top items (P0000, P0001) are what we call extension lists. Extension list are the way you group extensions together. For example if you wanted to have an all ring hunt group, you would build an extension list and place that in the hunt group to ring all the phones at the same time. The lower item (2105) is your hunt groups. This is where you would create the ringing destinations and call types. You can always press F1 for help when looking at the database programming and it will assist you with the screen you are looking at.