IE8 and opt-in versioning mechanism

Update 2008-01-23: See the followup on QA.

I have discussed a lot in the past about possible versioning mechanisms. A ‘meta’ element and http headers were two of the possibilities I had mentioned. Today, Chris Wilson (Microsoft and chair of the HTML WG) has announced in compatibility and IE8 that Microsoft worked with the WASP to propose an opt-in versioning mechanism.

The summary is

  1. “Quirks mode” remains the same, and compatible with current content.
  2. “Standards mode” remains the same as IE7, and compatible with current content.
  3. If you (the page developer) really want the best standards support IE8 can give, you can get it by inserting a simple <meta> element. Aaron gives more details on this in his article.

In the WASP article, it is explained as

<meta http-equiv="X-UA-Compatible" content="IE=8" />

My question to Chris Wilson:

Does IE8 support this opt-in mechanism when sent as an HTTP header only, without the meta in the document?

GET / HTTP/1.1
Host: www.example.org
X-UA-Compatible: IE=8

Update: Answers in the comments suggest that it doesn’t respect HTTP protocol.

5 thoughts on “IE8 and opt-in versioning mechanism

  1. The article proposes that HTTP servers can send an X-UA-Compatible header field, and individual documents can override what the server says with meta http-equiv=”X-UA-Compatible”.

  2. Either way, it seems to me that you’d want it in the document itself so that the compatibility mode would be retained even when the HTTP information is lost (such as when the document is saved locally by a user agent that doesn’t know to automatically add the meta element).

  3. @David: No. If I have to support this compatibility header to get the best standards support from IE I would prefer to simply handle it via web server configuration.

  4. I disagree with the web server configuration idea. As a server Admin you don’t know which pages require the new rendering and which ones don’t.

    Setting it in the server config would also preclude your users from submitting code that doesn’t work in IE8 that does in other browsers, this could be a nightmare for any website that wants to allow the use of Embeded objects or code in comments, or DataFeeds, or even potentially RSS.

    If you really wanted a server side solution I would think doing a forced include on every page would be the way to go. Which would also solve the problem for after the end user downloaded the page to their hard disk and wanted to view it later, as it would have the appropriate tags already included.

    more of my thoughts on this are at TakingTheBridge.com

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