MIX07 It took Microsoft six years to move Internet Explorer versions from 6 to 7. IE8 should be along a little quicker - it is slated for release within two years, less than three years after IE7's October 2006 debut.

But Microsoft has a big, big task on its hands: how to improve support for web standards in IE, without breaking millions of websites. Full standards compliance and backward compatibility do not go hand-in-hand for this web browser, alas.

So, Microsoft is preparing to invite community feedback via a blog on how best to square this circle.

Chris Wilson, IE group program manager, today told MIX07 that Microsoft may "need authors to opt into standards", suggesting a "compatible with IE 8.0" scheme.

In an interview with The Register, Wilson said he didn't want to take such a heavy-handed approach, but Microsoft doesn't want to break websites either. He said Microsoft couldn't make the necessary changes to IE through the standards process.

With the clock ticking on IE 8.0 and a long list of fixes, and new and updated features already in the product pipeline, Microsoft seems desperate to avoid a repeat of the engineering and PR nightmare that was standards compatibility in IE 7.0.

Some IE 8.0 features stem from problems that Microsoft encountered in IE 7.0. These were considered too big to tackle and attributable to Microsoft's use of its own technologies rather than industry standards.

According to Wilson, Microsoft has "lots more to do" in CSS - with bugs persisting in floating point elements and hasLayout - scripting and COM, and events and APIs not matching the DOM specification.

A key problem, though, is Microsoft's core layout engine, Trident, introduced 10 years ago. This has been updated but remains less compliant with official standards than competing browsers. Prior to shipment of IE 7.0, Microsoft admitted its new browser would fail the Web Standards Project's ACID2 browser compatibility test.

"It's challenging for us to support standards," Wilson said. The "core of Trident is great code".

While consulting the community on IE 8.0 should be commended, one goal could be to outsource responsibility on which standards Microsoft should support and for any resulting site breakages.

"By asking authors to say 'I want standards behaviors' means we don't have to worry about standards compatibility. That means we can break our compatibility with layout and CSS. We can change DOM APIs without breaking any current pages," Wilson said. ®