If you are merging, the merge results pane appears above or below the contributor panes and is not numbered. When you resolve differences between contributors, the changes appear in this pane.
If the contributor panes are arranged vertically, it is not as easy to differentiate the merge pane from the contributor panes. In this case, the merge results pane appears above the base contributor or below the to-version. (Remember that the contributor panes are numbered, and the merge results pane is not.)