I have been using the popular hack of serving plain HTML to MSIE, and XHTML
to everyone else:

RewriteEngine on
RewriteBase /
RewriteCond %{REQUEST_URI} \.xhtml$
RewriteCond %{HTTP_USER_AGENT} MSIE [OR]
RewriteCond %{HTTP_USER_AGENT} Lynx [OR]
RewriteCond %{HTTP_ACCEPT} application/xhtml\+xml\s*;\s*q=0\.?0*(\s|,|$)
RewriteRule .* - [T=text/html]

I also have Cache-Control set to "public". The dilemma I am facing (and please correct me if I am wrong) is that the Vary header has to be set to something that would prevent the public cache from, e.g., storing a response sent to Firefox and then serving it to MSIE. I think (again, correct me if I'm wrong), User-Agent can be added to Vary, and this would do the right thing. The problem is: this more or less defeats the purpose of public caching, given how many User-Agent strings are in use.

Is there a more efficient way? If so, how would I incorporate this into the above snippet?

Well! Seeing how the "hacking" with the content type was more IE6 trickery.


You can stop messing about with it now.

Thanks for the reply, ChrisHirst. But isn't it true that the same goes for
ANY MSIE<9? In other words, don't IE7,8 go into quirks mode when the
MIME type is application/xml+xhtml, just like IE6?

I recently asked a related question:
http://tycoontalk.freelancer.com/htm...rsion-1-a.html

and your reply seemed to suggest that IE7,8 act "quirky" on XHTML. No difference from IE6. Am I mistaken?

It's just the xml declaration being there that can trigger quirksmode

The MIME type + XML prolog issue was fixed in IE7