Is it semantically valid for adding a tag to a title tag?

Question

How in:

<header id="mainHeader">
        <hgroup>
               <h1>Title</h1>
               <h2>Sub Title</h2>
            </hgroup>
            <aside>
                <p>Some content within the header but isn't as important.</p>
                <p>Some content within the header but isn't as important line 2.</p>
            </aside>            
    </header>

The reason for this, as shown above, is that I have some content that belongs to the header (for example, a short block of information), but is only somehow connected, but not as important as the h1 and h2 tags.

Or should I just use a regular div?

Answer 1

In accordance with the drafts, HTML5 <aside>is content that is relevant to the main content, so this is not important, but related to the topics. The item <aside>may contain shocking news that relates to the boring content of a boring page.

, , HTML. "" , <header> <aside> <div class="foo" > , foo - .

Answer 2

, asides , - , - . , .

, , . , , , . , , , <section>.