In .org files—I've seen it only in a file with over 1k lines—emacs sometimes displays a secondary "line number" next to certain headings, like so:
The left-most gutter is populated by linum+, but the digit 8 on line 7 is what confuses me. The heading has no contents, just an empty line (line 8).
I believe the extra / floating digit gives the final line number of the collapsed heading...but what caused the number to show up in the first place? What mode is this coming from? Why doesn't it happen to all headings?
And so on. Thanks!