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Re: Page Validates But Mime Warning Continues

From: Sierk Bornemann <sierkb@gmx.de>
Date: Fri, 31 Aug 2007 14:39:07 +0200
Message-Id: <7C82887A-1484-480D-AA07-29A416A73261@gmx.de>
Cc: Tony Broome <tb777@samobile.net>, www-validator Community <www-validator@w3.org>
To: Dean Edridge <dean@55.co.nz>

Am 31.08.2007 um 13:54 schrieb Dean Edridge:

> Tony Broome wrote:
>> This is what the validator shows when trying to validate:
>> http://www.tonybroome.com/index.html
>> This Page Is Valid XHTML 1.1!
>> Result:
>> Passed validation
>> File:
>> C:\Documents and Settings\Owner\My Documents\My Web Pages\index.html
>> Encoding:
>> iso-8859-1
>> Doctype:
>> XHTML 1.1
>> Root Element:
>> html
>> Root Namespace:
>> http://www.w3.org/1999/xhtml
>> Important Warnings
>> The validator has found the following problem(s) prior to  
>> validation, which should be addressed in priority:
>> Warning Conflict between Mime Type and Document Type
>> The document is being served with the text/html Mime Type which is  
>> not a registered media type for the XHTML 1.1 Document Type. The  
>> recommended media type for this document is: application/xhtml+xml
>> But I have "application/xhtml+xml" in the header! I'm not working  
>> with Apachy or any server; just have a ministry website and want  
>> it to be as standards complient as possible. Is there anything I  
>> can do? A warning unheeded; is not, needed!
>> Sincerely,
>> Tony Broome
> <meta http-equiv="Content-Type" content="application/xhtml+xml;  
> charset=iso-8859-1" /> is being ignored by browsers as your server  
> is set to "text/html" and this overrides and meta tag value.
> You should change your document to HTML4 strict, as this is  
> supported by all browsers. XHTML is not supported by Internet  
> Explorer.

XHTML 1.0 is *surely* supported by Internet Explorer, as long as you  
serve this document with the MIME type "text/html", which surely is  
also allowed by the W3C XHTML 1.0 Recommendation for legacy browsers  
like IE, see http://www.w3.org/TR/2002/REC-xhtml1-20020801/#media  
with a "MAY" be used.
Internet Explorer does not understand and can't handle the MIME type  
"application/xhtml+xml", which is recommended for use with XHTML at  
all, and which SHOULD be preferred for XHTML 1.0 and SHOULD be used  
(and no other MIME type else) for XHTML 1.1 and XHTML 2.0, see http:// 
www.w3.org/TR/xhtml-media-types/ for details!
So, what isn't still supported by Internet Explorer, is *not* XHTML  
at all, but the use of the recommended MIME type for XHTML,  
"application/xhtml+xml". Knowing that, you have different  
possibilities to handle that.

If you want to serve correctly, use either XHTML 1.0 and serve it as  
"text/html" (then even IE does understand that), or serve as  
"application/xhtml+xml" (then IE doesn't understand, and there must  
be a serverside switch or something like that), which distuingishes,  
which client browser is used meaning if it does understand  
"application/xhtml+xml" or not. If yes, serve with the recommended  
mimetype "application/xhtml+xml", if no, stick to "text/html".
Under that circumstances, XHTML 1.1 only should be used, if that kind  
of switch does it work, or if all clients do accept "application/xhtml 
+xml", otherwise stick to XHTML 1.0.

If you serve an XHTML document as "application/xhtml+xml", you  
automatically serve it as an XML document and not as an SGML  
document, as you would do, if you serve it with "text/html".  
Consequentely it is useless to use a Meta element in the document  la
<meta http-equiv="Content-Type" content="application/xhtml+xml;  
charset=iso-8859-1" />, because the XML parser doesn't attend it. It  
is only attended (and so necessary) in SGML mode, meaning if you  
serve that document as "text/html". You have to advice the *server*  
to serve the right mimetype, meaning "text/html" for .html-documents  
and "application/xhtml+xml" for documents with the recommended  
extension .xhtml. If you do that, you can use content negotiaqtion to  
serve the right document to the right browser.

For details, also see

XHTML 1.0 Recommendation, 5.1. Internet Media Type

XHTML Media Types

Serving XHTML 1.0

Content-Negotiation Techniques to serve XHTML 1.0 as text/html and  

Serving XHTML with the Right MIME Type588

Serving up XHTML with the correct MIME type

See also the still open and still-not-be-solved Validator Bug #785 on  
http://www.w3.org/Bugs/Public/show_bug.cgi?id=785 and hot discussion  
on this item on www-validator@w3.org.

Sierk Bornemann
Sierk Bornemann
email:            sierkb@gmx.de
WWW:              http://sierkbornemann.de/
Received on Friday, 31 August 2007 12:39:26 UTC

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