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Rune · 07-26-2011, 05:55 AM

XHTML Introductions

XHRML stands for Extensible Hyper Text Markup Language and is a stricter and cleaner version of HTML.

XHTML is..
...nearly identical to HTML 4.01
...HTML defined as XML
... recommend by W3C

XHTML Support

XHTML is compatible with HTML 4.01. All current browsers support XHTML.

XHTML Syntax Rules
•Attributes names must be in lower case

Code:

<table width="100%">

•Attributes values must be quoted

Code:

<table with="100%">

•Attribute minimization is not allowed

Code:

<option selected="selected" />

•XHTML DTD defines required elements

All XHTML documents must have a DOCTYPE declaration. Also, <html>, <head>, <title>, and <body> elements must be present.

Code:

<1DOCTYPE Doctype goes here>

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

  <title>Title goes here</title>

<head>

<body>

  elements

</body>

</html>

XHTML and HTML Differences

XHTML is compatible with HTML 4.01. All current browsers support XHTML.

•Elements must be properly nested

Code:

<b><i>bold + italic</i></b>

•Elements must always be closed

Code:

<p>paragraph 1</p>

<p>paragraph 2</p>

<br />

•Elements must be in lowercase

Code:

<table>

 <tr>

   <tr>Cell 1</td>

 </tr>

</table>

•Documents must have one root element

All XHTML elements must be nested within the <html> root element.

XHTML DTD

In XHTML, the DOCTYPE declaration is mandatory and is always the first line in the document.

There are three XHTML DTDs:

•Strict
•Transitional
•Fameset

The most common DTD is XHTML Transitional

XHTML 1.0 Strict

Contains all HTML elements and attributes, but does not include presentational or deprecated elements. Framesets are not allowed. Markup must be well-formed XML.

XHTML 1.0 Transitional

Contains all HTML elements and attibutes, INCLUDING presentational and deprecated elements, Framesets are not allowed. Markup must be well-Formed XML.

XHTML 1.0 Frameset

Same as XHTML 1.0 Transitional, but allows frameset content.

XHTML 1.1

Same as XHTML 1.0 Strict, but allows addition of modules.