Since before 2009 or something. But it hasn't always been easy to find documentation about it, thanks to a combination I think of "simplifying" everything and

Since before 2009 or something. But it hasn't always been easy to find documentation about it, thanks to a combination I think of "simplifying" everything and Google not delivering correct results since somewhere around 2010. Thankfully now there is Kagi that actually makes a bug report if you provide them with an example that doesn't work.