Thanks for the clarification. So what you're saying is that absolute coordinate systems are not really absolute. That makes sense as I think about it. I can see how each part (component) needs it's own coordinate system that all it's geometry refers to (it own "absolute coordinate system"). But when a component is brought into an assembly, it will likely be positioned at some location other the assembly origin. So the component's "absolute" coordinate system will need to refer to the assembly's, but at some offset reflecting its position in the assembly. Either that, or else all the geometry in the component gets referred to a new "absolute csys". But that seems like a lot of trouble. So which is it?
Yes, the discussion did drift. But it hit upon another topic I've been wrestling with in NX, and that is the various coordinate systems (absolute, work, and datum) and how they're used. I have a lot of modeling work to do, and my biggest fear is that I'm going to make some error in how I setup datums or reference geometry that is going to haunt me later. I've come across several posts where that has happened to other users. So I appreciate the clarification.