-the alternatives. When `--ours` or `--theirs` option is in effect, however,
-these conflicts are resolved favouring lines from `<current-file>` or
-lines from `<other-file>` respectively.
+the alternatives. When `--ours`, `--theirs`, or `--union` option is in effect,
+however, these conflicts are resolved favouring lines from `<current-file>`,
+lines from `<other-file>`, or lines from both respectively. The length of the
+conflict markers can be given with the `--marker-size` option.