Saving map size

Ok I got two questions.

1. When you edit Object data does the game save just the changed data or the whole thing?

2. If you copy/paste a new unit in the "Object editor" does it create a whole new data sheet for that unit?

The reason for these questions is that I'm trying to save as much space as I can.


Thanks.

1)It just saves the changed data i beleive.

2) I'm not sure whether a whole new unit creates a data sheet. I beleive it still links to the same unit its copied from somehow only filling in parts it needs to.

Cool, thank you very much.