I'm just looking at a WordPress site that is behaving oddly (not mine, not a client's) which is a bizarre looking thing built on WordPress/Woocommerce and some godugly theme. At the top it has this: <!doctype html> <html lang="en-US" prefix="og: http://ogp.me/ns# video: http://ogp.me/ns/video# ya: http://webmaster.yandex.ru/vocabularies/" class="no-js"> <head> Code (markup): What's with the vocabularies thing?
https://github.com/bobuk/islands/blob/master/interactive-answers-eng.md should explain it. Not sure why one would use something like that though.
Not sure what you mean - Yandex is huge - third biggest after Google and Baidoo, I think. And OpenGraph is a farily common method / language-abstraction.