Mozilla opens hostilities with Microsoft
Mozilla has opened hostilities in the next browser battle by claiming Microsoft's Internet Explorer 9, due imminently, is not a "modern browser".
Paul Rouget, an evangelist for the not-for-profit firm behind Firefox, pointedly criticised IE9's compliance with website technical standards.
"IE9 is definitely better than IE8 and a step in the right direction, but I don't believe it to be a truly modern browser," he wrote.
Standards compliance has long been a weak point for Internet Explorer. Microsoft hopes to improve its reputation among web developers with the ninth edition, which is currently in the final stage of testing.
Bu Mr Rouget claimed problems remain which mean IE9 will lag behind Firefox.
"The reality is that IE9 is two years late," he said in a blog post.
In particular, he attacked Microsoft's claim that its new browser is 99pc compliant with HTML5, the new version of the language on which the web is based. It is designed to support more video and interactive elements in web pages.
Mr Rouget said Microsoft's figure was based on tests it created in-house rather than industry standards.
"It's not that surprising that they pass the very tests they used to design and develop the browser," he said.
According to an independent test cited by Mozilla, Firefox complies with 87pc of web standards overall, compared to 61pc for IE9.
Mr Rouget also provided a list of 17 Firefox technical features absent from IE9. But Microsoft has previously criticised the test used by Mozilla, which performs basic checks on whether technical features are present.
In its own blog post about standards, Microsoft argued the test doesn't "test the depth of an implementation or how well the feature's behavior matches the standard".
In total, versions of Firefox are together now more popular in Europe than versions of Internet Explorer, according to figures released last month.
Both browsers face a threat from Google's Chrome, however, which is based on the same rendering engine as Firefox, but is backed by a high-profile consumer marketing campaign.