function externalLinks()
{ 
    if (!document.getElementsByTagName)
    {
        return; 
    }
    var anchors = document.getElementsByTagName("a"); 
    for (var i=0; i<anchors.length; i++)
    { 
        var anchor = anchors[i];
         
        if (anchor.getAttribute("href") && anchor.getAttribute("rel")) 
        {
            var rels = anchor.getAttribute("rel").split(/\s+/);
            for (var j = 0; j < rels.length; j++)
            {
                if (rels[j].toLowerCase() == "external")
                {
                    anchor.target = "_blank";
                }
                break;
            } 
        }
    } 
}

function bindEvent(node, eventName, handler)
{
	// add via IE's method if available
	if (node.attachEvent)
	{
		node.attachEvent("on" + eventName, handler);
	}
	// add via DOM if not available
	else
	{
		node.addEventListener(eventName, handler, true);
	}
}

bindEvent(window, "load", externalLinks);