Hello, I have a few questions about COM, mass as well as  Principal Axes of Inertia and Principal Moment of Inertia in SolidWorks 2012-2013.

1. Is the pink coordinate the COM? As far as I recall, the coordinate with red X, green Y and blue Z (appears after choosing Tools>Measure) is the origin of the part or assembly.

2. On each pink coordinate axis, there is a small line. I noticed that when I rotate the part, these small lines are not parallel to the corresponding axis. Does that mean anything?

3. When opening a file, I am asked if I wish to run Import Diagnostics. If I say no, a window called FeatureWorks shows up and asks "Do you want to proceed with feature recognition? Do my answers to these questions affect the mass, COM and Moment of Inertia? As somebody else created the file, I have no idea how the proper real part is like. So, it is difficult for me to decide how to answer the questions of Import Diagnostics.

4. In Mass Properties, what does "Output coordinate system: -- default ---" means?

5. On the top left (feature tree), I see "Material <not specified>". Does that mean the mass, COM, and Inertia reported by Tools>Mass Properties are incorrect? How come the person who created the CAD model did not specify the material? Without such information, how can I obtain the correct data from the CAD file?

6. Although the values of Principal axes of inertia and principal moments of inertia (taken at the COM) are not zeros, the values of Moments of Inertia (taken at the COM and aligned with the output coordinate system) and that (taken at the output coordinate system) are all zeros. Is there somehting wrong? What does this mean?

Thanks.