I want to clear up some confusion. I have been getting several calls about the 2017 drawing format with Civil 3D. As you may be aware, 2017 does have the 2013 drawing format. So, nothing changed with the drawing format. However, the Civil 3D AEC object were upgraded.
What does this mean?
It means that you can NOT go backwards! Be careful! If you open a drawing in 2017, save it, open it up in 2016, you will get the dialog box below…
When you see this, you can click OK. Keep in mind, if you save this drawing in 2016, and then open it in 2017, all of the Civil 3D AEC objects will be hosed.