User Guide

106 Chapter 7 Using Web Development Languages
The Values tab is for validating regular expressions. All of these are unnecessary
for a standard XHTML document, so this configuration is complete.
5Click OK.
6 In the Settings dialog box, click Apply.
What the XHTML validator checks
When you configure the validator to check your code against the XHTML 1.0
specification, it checks the following rules:
• Tag element and attribute names must be in lowercase.
• Document must have an XHTML
doctype declaration.
• The document must have tags for
html, head, and body.
• The
title attribute must be in the head element.
• Elements must nest symmetrically; for example:
<i><b></b></i>, not <i><b></i></b>.
• Every tag must have an end tag (in pairs
<></>, or shortcut form </>, < />).
• Empty elements must have a corresponding end tag or contain an ending slash in
the start tag.
• Every attribute value must be quoted.
• An attribute value cannot be minimized. For example, you cannot have
<input
checked>
; it must be <input checked="checked">.
• If an element has a lang attribute, it must also have an xml:lang attribute.
Note
Many of these rules also apply to HTML.