No reason this couldn't accept a content type of application/htsl (for hypertext S-expression language, of course). I proposed something like this in a comment

No reason this couldn't accept a content type of application/htsl (for hypertext S-expression language, of course). I proposed something like this in a comment of mine a couple of months back: https://news.ycombinator.com/item?id=14931277 https://news.ycombinator.com/item?id=14931277