HTML5 is locked down. Developers, as of today, have a stable framework for the next several years and know what they can rely on in the specification, according to the World Wide Web Consortium (W3C) that oversees HTML5, part of the Open Web Platform.

The timing of today’s publication of the complete definition of HTML5, and its announcement as a candidate recommendation, is important, according to the W3C’s head of communications Ian Jacobs, as developers continue to build applications and websites with HTML5. Along with that announcement, the W3C also announced that HTML 5.1 is now a working draft.

Jacobs said improved video on the Web (driven by the television industry) and HD support for image functions are among the new features for the next version of the specification. And, the first draft of Canvas 2D Level 2, the drawing API that remains part of the HTML5 specification, was also announced today.

Jacobs cited a recent survey completed by Kendo UI (a division of development tools company Telerik) that showed that 82% of about 4,000 developers surveyed believe that HTML5 is important to their job within the next 12 months. Further, 63% of developers responding to the survey say they are already actively developing with HTML5, due to familiarity of language, cross-platform support and performance. Only 6% of respondents said they had no plans to use HTML5 in 2012.

So, even as HTML5 gains stability, 95% of developers responding to the Kendo UI survey said they have some level of concern about browser fragmentation. Jacobs said the next big effort over the next few years will be to meet broad interoperability requirements. “If you follow the data, there’s strong interoperability already,” he pointed out.

“But the W3C’s goal is not just interoperability across browsers, but across devices used. There are lots of producers of HTML in the world…content-management systems, e-mail clients. It’s a big effort; we have had support from lots of different industries.

“It’s useful to note there are some 80 companies in the working group, and there’s interest across the consortium for strong interoperability,” Jacobs continued. “The TV industry is keenly interested in a robust platform. They’re very keen on HTML testing. We have a modest test suite for HTML5, but we’re going to redouble our efforts.”

Jacobs noted that the W3C continues to collaborate with the Web Hypertext Application Technology Working Group (WHATWG), which formed because it viewed the W3C’s progress on HTML as too slow. So the W3C is working on the “snapshot” version of HTML, while WHATWG continues to advance what it calls the “living standard.”

In today’s announcement, the W3C “recognizes the work of Ian Hickson (from Google), who has been the editor of the HTML5 specification for nearly all of its existence.” Hickson is a part of the WHATWG effort.

“It’s a complex and fascinating mix of things that lead to a standard,” Jacobs said. “A well-written document is important, a test is important. The W3C feels building a consensus is important. But actual implementation is important. The WHATWG group believes what is implemented is super important. But there are a lot of factors involved (to create a standard)…discussion, review, integration with other technologies, timing. Having innovators out there being able to work quickly on new ideas, seeing what’s being taken up, is a great approach. Sometimes there are big successes, and sometimes we miss as well.”

As for the rest of the Open Web Platform, Jacobs noted progress in a number of different technologies.

The CSS Working Group, for example, is looking at features that let applications work well on tablets and APIs for device orientation. Also, the HTML Working Group has taken on work around responsive images, which will give the design community a better way to serve images in a website depending upon the context of the site, he explained. “It’s a useful complement to responsive design,” he said.

The W3C last week also published a recommendation for the Web Open Font Format, which defines fonts and enables them to be embedded in a Web page.