What happens if you open two buffers to view two parts of the same document (easy in Emacs, not possible in lots of editors)? If you switch focus or close one,

What happens if you open two buffers to view two parts of the same document (easy in Emacs, not possible in lots of editors)? If you switch focus or close one, what are you manipulating? Not the document. You could choose a different name (view?) but it's a different abstraction compared to a "document".