it’s direction. if I was going to make a formal thing out of it, each arrow would have a description. But it’s basically broad to narrow.
Mostly the program I’m using does the arrow automatically for “child-of” and I kept it. I’m looking for quick input without too much fussing right now, staying on the keyboard. I had DOS software long ago – a beautiful outliner thing – but never could find anything to match and it won’t work under emulators.