"rel=nofollow" is the only somewhat standard one. I have never heard of "rel=ugc" and I wonder if google made it up, does that work on bing and yandex? I mostl

"rel=nofollow" is the only somewhat standard one. I have never heard of "rel=ugc" and I wonder if google made it up, does that work on bing and yandex? I mostly use "rel=nofollow noopener noreferrer" which should cover most "use-cases" of spammers.