Originally Posted by Points
What exactly is the metadata.opf file, and how does it compare to content.opf? It seems to have metadata that could go in content.opf, and that I assumed would be there when I entered it in calibre, but isn't. Instead, it's in this separate file.
You are in dangerous territory if you can see that file.
metadata.opf is a DB recovery, backup of what you see in the Library view.
Content.opf is part of the book