w3c icon + 2.0 3.0 3.2 4.0
Netscape icon 1.0 2.0 3.0 4.0  
MSIE icon 1.0 2.0 3.0 4.0  
Mosaic icon 1.0 2.0      
Opera 1.0 2.1      

<ilayer>

container
start tagrequired
end tagrequired
Link to Site Map

implemented by Netscape but not supported by other browsers yet.

layer 3 content goes here

layer 4 content goes here