HTML/CSS/Basic Attributes/xmlns
"xmlns" declares a namespace for creating unique custom tags in the HTML document
<source lang="html4strict">
<HTML XMLNS:MSIE> <HEAD> <STYLE> @media all {
MSIE\:clientCaps {behavior:url(#default#clientcaps);}
} </STYLE> </HEAD> <BODY BGCOLOR="#FFFFFF">
</BODY>
</source>
