Organizing the Context Menu with the Registry

Question

I would like to learn how to organize Windows' context menu. I have figured out how to add items to the context menu, but this just adds them to the top of the menu, where everything up there is sorted alphabetically. However, there are items below the top area that seem to be in groups, separated by a line. I would like to know how I can manually do this with the registry. I am having a hard time finding what I want to do by searching for it, so I decided to ask here to see if anyone knows how.