If you want to understand what's going on, then go to the source. Either read the Microsoft documentation or read the documentation coming from an actual browser vendor working on this. At Mozilla, we talk about what we're doing so you're likely to get the best information with us.

http://weblogs.mozillazine.org/asa/archives/2012/02/building... and http://www.brianbondy.com/blog/id/129/