ConditionalComment is an UIComponent which renders a conditional comment. Conditional comments are an IE specific feature which enables the developer to (out)comment blocks of HTML depending on whether the client is using IE and if so even which version. They are often seen in combination with CSS stylesheets like so:

 <!--[if lte IE 7]>
   <link rel="stylesheet" href="ie6-ie7.css" />
 <![endif]-->
 

However, Facelets renders them HTML-escaped and if javax.faces.FACELETS_SKIP_COMMENTS context param is set to true then it will even not be rendered at all. You would need to workaround this with an ugly <h:outputText escape="false">.

 <h:outputText value="&lt;!--[if lte IE 7]&gt;&lt;link rel=&quot;stylesheet&quot; href=&quot;ie6-ie7.css&quot; /&gt;&lt;![endif]--&gt;" escape="false" />
 

This component is designed to solve this problem.

 <o:conditionalComment if="lte IE 7">
   <link rel="stylesheet" href="ie6-ie7.css" />
 </o:conditionalComment>
 

Note that you cannot use this with <h:outputStylesheet> as it would implicitly be relocated as direct child of <h:head>.