Some must have lines for Transitional type:
<!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">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>DaYLoG</title>
<script src="js/jquery-1.2.3.pack.js"></script>
<script src="js/runonload.js"></script>
<script src="js/daylog.js"></script>
<link href="css/tutorial.css" media="all" type="text/css" rel="stylesheet">
</head>
*XHTML elements must be properly nested
*XHTML elements must always be closed
*XHTML elements must be in lowercase
*XHTML documents must have one root element
*Attribute names must be in lower case
*Attribute values must be quoted
*Attribute minimization is forbidden
*The id attribute replaces the name attribute
*HTML 4.01 defines a name attribute for the elements a, applet, frame, iframe, img, and map. In XHTML the name attribute is deprecated. Use id instead.
*To interoperate with older browsers for a while, you should use both name and id, with identical attribute values
*The XHTML DTD defines mandatory elements
*All XHTML documents must have a DOCTYPE declaration. The html, head and body elements must be present, and the title must be present inside the head element.
*The DOCTYPE declaration is not a part of the XHTML document itself. It is not an XHTML element, and it should not have a closing tag.
*An XHTML document consists of three main parts: the DOCTYPE, the Head, the Body
*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">
Use this when you want really clean markup, free of presentational clutter. Use this together with Cascading Style Sheets. The Strict DTD includes elements and attributes that have not been deprecated or do not appear in framesets.
XHTML 1.0 Transitional
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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. The Transitional DTD includes everything in the strict DTD plus deprecated elements and attributes.
Validate page here:
http://www.w3schools.com/xhtml/xhtml_validate.asp