Conditional comments for IE
From Invenzzia wiki
Sometimes it is necessary to use a special type of comments called "conditional comments". To use them in your source code, you have to surround it with CDATA and opt:literal instruction with "transparent" type attribute:
<opt:literal type="transparent"><![CDATA[
<!--[if IE 6]>
Special instructions for IE 6 here
<![endif]-->
]]></opt:literal>

