Heading content defines the title of a section, whether marked by an explicit sectioning content element or implicitly defined by the heading content itself.
Heading content category has dependency to the flow content category and heading content category cannot have child elements from other content categories.
HTML elements belonging to this content category are (Click on the html element to view an example): <h1>, <h2>, <h3>, <h4>, <h5>, <h6>, <hgroup>.