edik

If FacadeX is active, the public WordPress sites are sent with the xhtml mime type. The internal sites like the administration panel and the login screen, which have many xhtml syntax errors, are still sent with the standard mime type.
You must ensure that your public sites have valid XHTML, otherwise you will get parsing errors in your browser.

FacadeX

Sends public sites with the XHTML mime type. The internal sites, which have many XHTML errors, are still sent with the HTML mime type.

John Godley

HTML Purified replaces the default WordPress comments filters with HTML Purifier, a super HTML filtering 
library.
<blockquote>
HTML Purifier is a standards-compliant HTML filter library written in PHP. HTML Purifier will 
 not only remove all malicious code (better known as XSS) with a thoroughly audited, secure yet 
 permissive whitelist, it will also make sure your documents are standards compliant, something 
 only achievable with a comprehensive knowledge of W3C’s specifications.
</blockquote>
An additional feature of HTML Purifier is that it will produce valid well-formed XHTML code, something 
which KSES does not do.
Features:
<ul>
<li>Configurable KSES or HTML Purifier</li>
<li>Configurable list of HTML elements and attributes for both KSES and HTML purifier</li>
<li>Additionally process comments with HTML Tidy</li>
<li>URL blacklist</li>
<li>Fully localized (and awaiting translations)</li>
<li>Automatically escape PHP or anything inside backticks</li>
</ul>
HTML Purifier is available in:
<ul>
<li>English</li>
<li>Spanish, thanks to José Cuesta</li>
<li>Belorussian, thanks to Marcis Gasuns</li>
<li>Russian, thanks to Ilyuha</li>
<li>Uzbekistan, thanks to Alexandra Bolshova</li>
<li>Dutch, thanks to Pieter</li>
<li>German, thanks to Andreas Beraz</li>
<li>Polish, thanks to Kasia Ciszewski & Dawid Śpiechowicz</li>
<li>Romanian, thanks to Alina @ InboxTranslations.com</li>
<li>Lithuanian, thanks to Nata Strazda</li>
<li>Ukranian, thanks to Iflexion Design</li>
</ul>
<h3>Documentation</h3>
Full documentation can be found on the <a href="http://urbangiraffe.com/plugins/html-purified/" rel="nofollow ugc">HTML Purified</a> page.

HTML Purified

HTML Purified replaces the default comments filters with the more secure HTML Purifier.

FacadeX vs HTML Purified