Mozilla Chief Technology Officer Brendan Eich and Microsoft's Chris Wilson are trading heated rhetoric over the proposed next version of ECMAScript, better known as JavaScript.

Microsoft is quibbling with the ECMAScript Edition 4 effort, which is supported by Mozilla, maker of the Firefox browser. "As I've frequently spoken about publicly, compatibility with the current web ecosystem -- not 'breaking the Web' -- is something we take very seriously," Wilson wrote on the Internet Explorer team blog this week. "In our opinion, a revolution in ECMAScript would be best done with an entirely new language, so we could continue supporting existing users as well as freeing the new language from constraints."

Eich is the creator of JavaScript, a programming language that has become a bedrock Internet technology, helping drive much of the rich content and information now common on the Web. Microsoft's implementation of it is known as JScript.

Wilson is the platform architect of Microsoft's Internet Explorer platform team. He wrote on his personal blog that Microsoft's position has been misunderstood: "Sadly, this seems to be turning into an 'ES4: yes or no' battle. That's unfortunate, because I don't think anyone should settle into the trenches, and I don't think the other Microsoft guys ever intended to say "everything about ES4 is bad."

"I also think it's a shame that the response to any dissent has equated to shouting the dissenters down," he added.

Writing on his blog in response, Eich accused Wilson of spreading lies.

"You seem to be repeating falsehoods in blogs since the Proposed ECMAScript 4th Edition Language Overview was published, claiming dissenters including Microsoft were ignored by me, or 'shouted down' by the majority, in the ECMAScript standardization group," Eich wrote. "Assuming you didn't know better, and someone was misinforming you, you (along with everyone reading this letter) know better now. So I'll expect to see no more of these lies spread by you."

As for ECMAScript 4's purported shortcomings, Wilson wrote that the proposed new standard may result in complications and incompatibilities with existing Web sites and applications.

"As I understand it, on the other hand, the ES4 proposal introduces a lot of new language functionality that essentially changes the character of the language," he said. "I don't personally have a problem with that language as a language -- but I think grafting that different-in-character-language together with a compatible-and-performant implementation of the Javascript of today is both super-hard (if even possible) to get right, and is ignoring the bigger problems of language-for-web, namely interoperating with all the script that is out there."

Eich charged in turn that Microsoft's arguments are self-serving. "At best, we have a fundamental conflict of visions and technical values between the majority and the minority," he wrote. "However, the obvious conflict of interest between the standards-based web and proprietary platforms advanced by Microsoft, and the rationales for keeping the web's client-side programming language small while the proprietary platforms rapidly evolve support for large languages, does not help maintain the fiction that only clashing high-level philosophies are involved here."