> The frame element has been completely removed, the hgroup element is gone, and so is the dir element. acronym is deprecated in favour of abbr. isindex, plaint

> The frame element has been completely removed, the hgroup element is gone, and so is the dir element. acronym is deprecated in favour of abbr. isindex, plaintext, xmp, and listing are all dead. Those are all basically cosmetic/layout related, though. The text itself is still perfectly readable.