Yeah @Mike Linksvayer has the right link. What it means is that the standard has gone through the (lonnnnng) process of group consensus on making a standard that the group believes is ready to be submitted to the W3C Advisory Committee to be accepted or not as an official standard. It implies a high level of confidence, and a mountain of work, to get to that stage. Hopefully next we'll wee the committee sign off on it being a recommendation.