Microsoft's scheme has previousely been slashdotted. It has caused an uproar in the web community. According to the scheme, authors must put Microsoft-specific <meta> tags into their pages in order for them to be rendered correctly. I doubt Acid2, nor Acid3 will have Microsoft extensions in them.A second scenario could be that Microsoft requires Web pages to change the default settings by flagging that they really, really want to be rendered correctly. Web pages already have a way to say this (called "doctype switching," which is supported by all browsers), but Microsoft has all but announced that IE 8 will support yet another scheme. If it decides to implement the new scheme, the Acid2 test — and all the other pages that use doctype switching — will not be rendered correctly.