So I found this video this morning via Luke Johnson on twitter who runs whatrevitwants blog. This is a YouTube video describing the project coordinate system in Revit. There are a lot of potential problems to run into when dealing with the coordinate system. This video gives a good overall and detailed explanation of how to set up the system in your Revit project. The authour of the video cwm9 on YouTube also discusses: Project and survey points, coordinates, clipped and unclipped modes and finally true north settings in Revit.
“The coordinate system for Revit has been rehashed many times on blogs and posts, but has been clear as mud for me, and I suspect a lot of other people. So I took the time to really figure out it, and here’s a 30 minute explanation of how Revit’s coordinate systems work, interrelate, how true north works, and how to put multiple copies of a building on a site.”
cwm9’s YouTube channel