Should it stay part of the specification here is how to use it:
The hgroup element is used to group headings together. It must contain at least two of the heading elements and no other information. It is for grouping a title with a subtitle. It can contain different combinations such as <h1> with <h2.> or <h3> with <h4> etc.
For those of you that create headings with display: inline ( to get rid of the unsightly gap) and then add a <br> you will not longer be able to do this because it will not validate if a <br> is inside an hgroup. You need to play with the margins inorder to reduce the gap.
Attributes: All Global