Thanks. I posted that comment before they had added support - https://news.ycombinator.com/item?id=48353325 - didn't know situation had changed.

But it's something I think developers should think about if they rely on caching. If it took Cloudflare this long to support this, there may be other systems which still don't.

Link to Roy Fielding comment:

https://lists.w3.org/Archives/Public/ietf-http-wg/2013JanMar...