I figured some of it out. Here is a 1" diameter circle who's center is at 2", 2".
I inserted that into an assembly and inserted that assembly into a drawing. It looks like this:
Notice the blue dashed line? I can drag that model around anywhere I want. If I select the measure command and measure the center of that circle it tells me that it is at 2", 2" no matter where I drag the blue model around on the drawing. In other words, any measure you do will be as if the lower left corner of the blue box is the origin.
When I output a DXF file the coordinates are output with the lower left corner of the paper (the tan area) as the origin rather than the blue boundary. If I drag the model somewhere else the coordinates change. The DXF coordinates are dependant upon where you place the model.
I either need to control where that model is placed by making sure the boundary (the blue line) is at 0,0 or be able to measure the center of the circle relative to the paper. Any ideas?