Posted by Alan J. Flavell on 02/05/06 17:45

On Sun, 5 Feb 2006, Toby Inkster wrote:

> And with a little creativity, you could serve up a transparent GIF
> to any browsers with "MSIE" in their user-agent string, and a PNG to
> everyone else.

Don't do that - it's bad in principle, and works badly in practice.
For all the usual reasons.

PNG versus GIF can be successfully negotiated on the basis of the
client's initial Accept: header. As far as I recall, even MSIE gets
this correct enough to be useful - at least on its initial request.

Apache's MultiViews will do this pretty much for free, out of the box,
if you let it.

(MSIE has a silly habit of sending "Accept: */*" when reload is used,
but I guess we can live with that. Workarounds would likely have
negative impact on real WWW browsers, so I won't suggest those. But
your proposed kludge would have negative impact on /all/ of the real
WWW minority browsers that feel they need to masquerade as MSIE in
order not to get locked out by idiot webmasters.)

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