I don't even know. 😂 The highlight json looks wildly different, depending upon which client produces it, and the spec is full of fiddly blah blah, but I just have content and an r-tag with a URL and it works everywhere.

Wish the spec contained a minimal example of an event highlighting a note and an event highlighting a web page.

Weird, to me, to make a spec defining a new kind, and leave out any examples.