AFAIK NS4 doesn't support that tag. It's part of the HTML DOM which NS4 doesn't support. Netscape decided to support only their own ideas instead of the then-draft W3C specification which Microsoft decided to support. The result was of course the ultimate demise of Netscape (though there were more technical reasons, this was an important one).
In any case, NN 4.7 is ancient. Modern versions of Netscape will support the innerHTML attribute (it's an attribute, not a tag). [ June 08, 2004: Message edited by: Bear Bibeault ]