XHTML DTD
The XHTML standard defines three Document Type Definitions.
The most common is the XHTML Transitional.
<!DOCTYPE> Is Mandatory
An XHTML document consists of three main parts:
- the DOCTYPE
- the Head
- the Body
The basic document structure is:
<!DOCTYPE ...>
<html>
<head>
<title>... </title>
</head>
<body> ... </body>
</html>
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The DOCTYPE declaration should always be the first line in an XHTML document.
An XHTML Example
This is a simple (minimal) XHTML document:
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>
<head>
<title>simple document</title>
</head>
<body>
<p>a simple paragraph</p>
</body>
</html>
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The DOCTYPE declaration defines the document type:
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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The rest of the document looks like HTML:
<html>
<head>
<title>simple document</title>
</head>
<body>
<p>a simple paragraph</p>
</body>
</html>
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The 3 Document Type Definitions
- DTD specifies the syntax of a web page in SGML.
- DTD is used by SGML applications, such as HTML, to specify rules that
apply to the markup of documents of a particular type, including a set of
element and entity declarations.
- XHTML is specified in an SGML document type definition or 'DTD'.
- An XHTML DTD describes in precise, computer-readable language, the allowed
syntax and grammar of XHTML markup.
There are currently 3 XHTML document types:
- STRICT
- TRANSITIONAL
- FRAMESET
XHTML 1.0 specifies three XML document types that correspond to three DTDs: Strict, Transitional, and Frameset.
XHTML 1.0 Strict
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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Use this when you want really clean markup, free of presentational clutter.
Use this together with Cascading Style Sheets.
XHTML 1.0 Transitional
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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Use this when you need to take advantage of HTML's presentational features
and when you want to support browsers that don't understand
Cascading Style Sheets.
XHTML 1.0 Frameset
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">
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Use this when you want to use HTML Frames to partition the browser window
into two or more frames.
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