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Re: XHTML

From: Herr Christian Wolfgang Hujer <Christian.Hujer@itcqis.com>
Date: Tue, 8 Apr 2003 11:13:20 +0200
To: bea944@aol.com, www-html@w3.org
Message-Id: <200304081113.23183.Christian.Hujer@itcqis.com>

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Hi,

Am Dienstag, 8. April 2003 08:01 schrieb bea944@aol.com:
> Hi
> I just wanted you to know that there is one tag that gives everyone
> problems with is the <br/> seems that netscape and exployer 6.0 does not
> like. I'm taking a free on line XHTML course I have tried to explain to all
> the new people that it seems to be a broswer problem.I wish that there was
> one simple language to do basic website design for example XML I like it
> because it is easier and more powerful than HTML or XHTML is there a reason
> why that we cannot have one language that can do all?

XML is a language without any semantics, basically it isn't a language at all. 
It's just a language concept, like "human language", which is just a concept 
the "real languages" like English, Chinese etc. are based on.

We can't talk in "just human language". Elements and Attributes of XML need 
some semantics associated with them. Languages that provide such semantics 
(like English and Chinese for human languages) are XHTML, MathML, SVG, SMIL, 
XML Schema, XSL FO, XSLT and many more.

You can't use XML (just XML without anything else) to design a website. And if 
you use XML+CSS, you don't have hyper links, inline images (I think CSS2 
could do that, but most user agents don't fully support CSS2, especially 
Internet Explorer misses many features), you don't have forms, JavaScript and 
inline stylesheets (the only feature of HTML you really could live without).

Theoretically it could be possible to introduce another language that 
describes the semantics.
One such language is CSS. That also shows the problems. Languages describing 
semantics, in the case of CSS it is presentation and in a limited sense also 
some behaviour, are restricted.
Currently, IMHO the W3C tries to extend CSS in a way that it is possible to 
completely (or at least close to it) describe XHTML in it, which is a very 
good approach indeed.

But there will always be fields not covered by CSS, and CSS is somewhat 
restricted anyway, so other languages will always be required.


To your <br/>-problem: As far as I know, <br/> is absolutely no problem for 
Internet Explorer, it only is a problem for Netscape browser prior to version 
6, where you must insert a space before the /: <br />. That's a well known 
issue, the HTML compatibility mode of XHTML suggests you put spaces in front 
of the / for an EmptyElemTag.
See 
http://www.w3.org/TR/xhtml1/#guidelines
C.2


Considering XML / XHTML / HTML be aware of the following facts:
1. XHTML adds some semantics that cannot be expressed in XML+CSS, e.g. 
Hyperlinks, Scripts, embedded Stylesheets.
2. MIME Types
HTML: text/html
XML: application/xml or text/xml
XHTML 1.0: application/xhtml+xml or, if in compatibility mode as in 
http://www.w3.org/TR/xhtml1/#guidelines C.2, also text/html
XHTML 1.1, XHTML Basic: application/xhtml+xml
3. The only user agent of that I know it accepts application/xhtml+xml on HTTP 
Request level is Mozilla / Netscape 7.
4. Opera and Konqueror at least know how to deal with XHTML, but they do not 
tell the server they can (no Accept application/xhtml+xml in the HTTP 
Request). They still have some problems in some fields, e.g. JavaScripts or 
Stylesheets in XHTML not working at all or only very limited.
5. Internet Explorer doesn't know how to deal with XHTML at all. It just 
treats XHTML as HTML and ignores errors caused by the / on empty element 
tags.

So in real life, you'd do exactly one of the following, if you want to be 
standards compliant:
1. Don't use XHTML, just use HTML 4.01 and send it as text/html
2. Use XHTML 1.0 in compatibility mode and send it as text/html
3. Ignore Internet Explorer and send XHTML as application/xhtml+xml always
4. Use two versions, XHTML and HTML 4.01 and use a content negotiation with 
preferring text/html over application/xhtml+xml, hazarding the consequences 
that Opera and Konqueror will be served HTML 4.01 because they do not Accept 
application/xhtml+xml at HTTP-Level, but at least Mozilla-based user agents 
will be served the XHTML version.

Also know that currently most XHTML user agents do not have full support for 
the HTML DOM when running in XML/XHTML mode. E.g. the "document.write() not 
supported" issue in Mozilla.


Bye
- -- 
ITCQIS GmbH
Christian Wolfgang Hujer
Geschäftsführender Gesellschafter
Telefon: +49  (0)89  27 37 04 37
Telefax: +49  (0)89  27 37 04 39
E-Mail: Christian.Hujer@itcqis.com
WWW: http://www.itcqis.com/
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Received on Tuesday, 8 April 2003 05:14:54 GMT

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