What is the purpose of color in MoI?

 From:  mickelsen
3506.1 
Michael,
I have come to realize that you include certain features in the software with very specific uses in mind, and that if I don't realize what those uses are then I lose a lot of the functionality of the software, and can even cause myself some trouble. With that in mind, could you refer me to places in the documentation that can teach me what you intend color to be used for in MoI? I had gotten the impression that it could be used to create groups of objects that were linked together, but if that is true, I don't understand how.

I know you're busy so give me a chance to read up on it before I ask specific questions.

Thanks,
Mark