Use of HTML/XHTML Standards

The use of web standards and practice of validating web content insures interoperability with a wide range of technologies that render web content.

Resources for Standards Based Design

W3C HTML Validation Service

The W3C HTML Validation Service for HTML documents can be used to determine if HTML/XHTML documents comply with specifications.

The following elements must be part of the document for the automatic validation of web resources:

  1. Include a DTD at the beginning of the document. Common document types:
    • HTML 4.01 Transitional: In general, supports the inclusion of deprecated elements and attributes
    • HTML 4.01 Strict: Cannot use deprecated elements and attributes
    • XHTML 1.0 Transitional: Reformulation of HTML 4.01 transitional to comply with XML rules
    • XHTML 1.0 Transitional: Reformulation of HTML 4.01 strict to comply with XML rules
  2. Language specification
  3. Characterset information

HTML 4.01 Transitional Source Code Example

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">

<HTML LANG="EN-US">

<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html;charset=iso-8859-1">
....
</HEAD>

<BODY>
....
</BODY>

</HTML>

HTML 4.01 Strict Source Code Example

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Strict//EN" "http://www.w3.org/TR/REC-html40/strict.dtd">

<HTML LANG="EN-US">

<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html;charset=iso-8859-1">
....
</HEAD>

<BODY>
....
</BODY>

</HTML>

XHTML 1.0 Transitional Source Code Example

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US" lang="en-US">

<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
...
</head>

<body>
...
</body>

</html>

XHTML 1.0 Strict Source Code Example

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US" lang="en-US">

<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
...
</head>

<body>
...
</body>

</html>