3.2.7.4 Implicit ARIA Semantics [1] currently limits the role attribute on the section element to the following values:

> alert, alertdialog, application, contentinfo, dialog, document, log, 
> main, marquee, region, search, status or presentation

However, the section element [2] could conceivably be used to mark up tabpanel content in a tab widget:

> The section element represents a generic section of a document or 
> application. A section, in this context, is a thematic grouping of content.
> Each section should be identified, typically by including a heading 
> (h1-h6 element) as a child of the section element.

In fact, the non-normative example that follows explicitly makes note of this use case:

> Examples of sections would be chapters, the various tabbed pages in a 
> tabbed dialog box, or the numbered sections of a thesis. A Web site's home 
> page could be split into sections for an introduction, news items, and 
> contact information.

Here is a simple example of this use case [3].  This example currently throws a validation error.

Recommend adding 'tabpanel' to list of roles allowed on the section element in 3.2.7.4 Implicit ARIA Semantics [1]

[1] http://www.w3.org/html/wg/drafts/html/master/dom.html#sec-implicit-aria-semantics
[2] http://www.w3.org/html/wg/drafts/html/master/sections.html#the-section-element
[3] https://rawgit.com/clrux/html5-tabpanel-test/master/index.html