Haavard Moen, who works in Opera's desktop QA group, was more blunt in his criticism.
In a personal blog post, Moen blasted Hachamovitch. "HTML5 is not native. It is not supposed to be native. It is silly to even attempt to tie HTML5 to a specific platform," Moen wrote. "Hachamovitch should be ashamed of himself for signing his name to such a shoddy piece of dishonest marketing nonsense."
The lack of a clear definition of "native HTML5" forced Lawson and others to speculate on what Hachamovitch meant.
"It could be their attempt to co-opt [the term] 'HTML5' for themselves, and there are many people and organizations that would like to do the same," said Lawson. "But I'm guessing they mean hardware-accelerated HTML5."
If the second is what Microsoft means, it's a continuation of the public relations and marketing effort to cast IE9 -- and by extension IE10 -- as the best browser for Windows 7. "Microsoft is trying to say that IE9 supports HTML5 natively fast using hardware acceleration only on the latest and greatest OS," said Lawson.
Eich of Mozilla saw it Lawson's way.
"They are talking about performance, or rather the lack of it due to the lack of hardware-accelerated graphics on Windows XP," Eich said on Bugzilla.
But others in the same thread lampooned that definition.
"I don't think general-purpose hardware actually supports 'native HTML5.' Wake me up when we have HTML5 co-processors," said Chris Jones, a Web designer and developer who contributes to Firefox.
Microsoft has been beating the drum about browser hardware acceleration since it launched the first public preview of IE9 a year ago. More recently, it has promoted the idea that a browser is only as good as the operating system it runs on, and that by extension, browsers that run on non-Windows OSes, or even on the 10-year-old Windows XP, are sub-standard.
Last month, for instance, Hachamovitch said that rivals like Google and Mozilla "dilute their engineering investments" by creating browsers for the Mac, Linux and Windows XP.
Microsoft has also repeatedly used the phrase "lowest-common denominator" to describe how it sees browser development on XP, Mac and Linux. This week, it applied the same to its four-year-old Windows Vista when it said its next browser, IE10, would not run on that OS.
But the best line came from Beltzner, who first poked Microsoft on Bugzilla.
"We don't meet the requirements [of 'native HTML5'] until we manage to ship Firefox 4 on Internet Explorer on Windows 7," Beltzner said.
Sign up for Computerworld eNewsletters.