This is precisely how Org mode works in Emacs, IIRC. Now I'm curious who was the first person to invent this syntax—like you say, it seems like a very natural c

This is precisely how Org mode works in Emacs, IIRC. Now I'm curious who was the first person to invent this syntax—like you say, it seems like a very natural choice, so I'd be surprised if it doesn't have a long history of some sort.