The World Wide Web Consortium expects HTML5 to reach “recommendation” status in 2014, announced after today’s “last call” for comment on the technical content of the specification.

The W3C’s ultimate goal is strong interoperability with other technologies in the ecosystem, such as authoring tools, blogging tools, content management systems, e-mail systems, audio and video tools, and many more, according to Ian Jacobs, the W3C’s head of communications. Those groups “rely on stability” in the underlying platform to ensure interoperability. And that, he said, takes time to get right.

“If you invest the term ‘standard’ with seriousness, you need interoperability, and testing is a part of that,” Jacobs said. “First we get consensus about the technical content of the specification, then work on implementation by building out a test suite and documentation.”

What this cutoff does, he said, is to say to the industry, “We think we’re done, and would like you to confirm that we’re done. This is the time to handle those comments.”

HTML5 is the cornerstone of what the W3C is calling the Open Web Platform, a moniker meant to emphasize the evolution of the Web from a document-sharing platform to a platform for linked data and applications presented in a richer format, including audio, video and graphics. This brings the platform closer to the W3C’s vision of a “semantic Web” that describes things in ways computer applications can understand.

For now, Jacobs said there are perhaps 100 specifications in the Open Web Platform, with dozens of groups working on a host of technologies, including SVG, CSS, 3D animation and Web fonts.

“People want to use the Web in all kinds of ways,” said Philippe Le Hégaret, the W3C’s interaction domain leader. “So we’re addressing more and more use cases. For example, real-time communication is an area where people are looking to extend the set of capabilities the Web platform will have in the future.”

One area where there is not yet consensus is the video codec; the W3C has said it is encouraging the industry to choose a standard to prevent developers from having to write their applications multiple times to support different codecs.

Le Hégaret said testing on HTML5 began last year, but he said that tens of thousands of tests will need to be completed before the specification can be called a standard.

Jacobs added that the W3C’s role in testing is to gather the test cases. “We’re not here to evaluate and certify the implementation,” he said. That would be up to each software provider leveraging the specification to complete.

The “last call” period is set to close in May 2011. According to the W3C, there are more than 50 organizations participating in the HTML Working Group.