The HTML5 <hgroup> tag is mainly used as a representation for the heading of a section. The HTML5 <hgroup> tag is an integral part when creating multiple headings or subheadings and the tags <h1> to <h6> are incorporated within the HTML document.
The HTML5 <hgroup> tag is not present in HTML4. Making the Global Attributes and Event Attributes work with HTML5 <hgroup> tag is not a problem since these are also compatible with the tag. More importantly, the HTML5 <hgroup> tag is also compatible with the major web browsers like Firefox, Google Chrome, Safari, Opera and Internet Explorer so there should be no concerns when using this tag.