Hi Julian,

Thanks for your answer and sorry for being late with mine (I was ill). I've added a
   Header set Cache-Control: "private"
for all my html and hope its technically correct now. I did not look into the possibility
to provide a "Vary" response header yet, but if you think it's the better solution, I would
be grateful for a pointer.

On 23/10/2007, Julian Reschke <julian.reschke@g...> wrote:
> > In a small paragraph, under the heading "Can I serve one resource with
> > two distinct MIME-types?", he wrote:
> > While it's theoretically possible, I don't know any way to do it
> > without breaking some important aspects of HTTP (such as proxying, or
> > the HTTP PUT method) - that is, the method I know using RewriteRules
> > doesn't set headers such as ETag as it should.
> 
> Of course you *can* do that; it's called content negotiation (yes, even
> if the response *body* is the same).
> 
> You are doing content negotiation here, because your server's response
> varies based on the "Accept" request header. Thus you will either have
> to disable (public) caching, or provide a "Vary" response header that
> would enable intermediates to serve the correct variant.

Your remarks also made it clear, that a negotiated response is a problem for any
intermediates (proxies), if not declared as such. I used the term "content negotiation"
as established by Apache, but would prefer "negotiated response" (with a negotiated
response-header OR with a negotiated content OR both).

> I don't think that serving XHTML as text/html is "state of the art",
> unless the XHTML happens to be valid HTML as well.
My XHTML is _not_ valid HTML in any sense (namespace,  self-closing <br/> and <div/>'s),
but I don't care too much to serve a XHTML lookalike to a tagsoup browser!

Best regards, Manfred