Envoyé par IEBlog
We’re encouraging site developers to use a standards doctype and no X-UA-Compatible Meta tag or HTTP header when targeting IE9’s Standards mode. This helps us all reach the goal of running the same standards-based markup.
If you have a legacy site that relies on IE7’s interpretation of Standards mode use the X-UA-Compatible Meta tag or HTTP header to target IE7 Standards mode. Here’s an example that combines values so that IE8 renders a webpage in IE7 Standards mode while IE9 renders the webpage in IE9’s Standards mode: