Hey Steve - you now understand how I felt when I first saw the XLS sheet with the list of materials.....
Nevertheless, what I understand is that pine wood marked as "NOM" are the ones used for constructing the frame where there is some tolerance for inaccuracies, while the "ACTUAL" is used for areas where things have to be precise.
If you take your time to build the observatory, I believe it can become a very rewarding process.
I also spoke with Darebin council (I'm located in Reservoir) and they've confirmed I don't require a permit or approval for the shed.
Now I need to decide if I'm going to use a concrete slab or have the shed floating in the air on 4 or 6 poles cemented into the ground!