function addExtern()
	{
		var i;
		var j;
		var parameter;
		var extensions;
		var extension;
		var href;
		
		// the following extensions will get a extra onClick event handler. 
		extensions = new Array('.pdf','.doc');  
		linkList = document.links;       
	
		//loop trough all href's
		for (i = 0; i < linkList.length; i++)
			{
			//loop trough all extensions
				for (j = 0; j < extensions.length; j++)
					{
						href = linkList[i].href.toLowerCase();
						extension = extensions[j].toLowerCase();
						if (href.indexOf(extension) > -1)
						{				
							//add onclick handler 
							var link = linkList[i];
							if (link.addEventListener) //addEventListner is supported by Gecko based browsers  and Opera (DOM2)
								{
									link.addEventListener('click', urchinTrackerProxy, false); 
								} 	
							else if (link.attachEvent) //attachEvent is supported by IE
								{
									link.attachEvent('onclick', urchinTrackerProxy);
								}
							break;			
						}	
					}
			}
	}
	
	function urchinTrackerProxy(evt)
	{
		var href;
		var parameter;
		// 'target' for Gecko browsers, Opera etc, 'srcElement' for IE
		var ie_var = 'srcElement';
		var dom2_var = 'target';
		//href of the clicked link is what we want 
		var prop_var = 'href';
		
		//get the href of the clicked link
		evt[dom2_var] ? href = evt[dom2_var][prop_var] : href = evt[ie_var][prop_var];
		
		//get the filename of the clicked link
		parameter = '/download/' + href.substring(href.lastIndexOf('/')+1);
		parameter = parameter.toLowerCase();
		
		urchinTracker(parameter);
	}
	
	/*function urchinTracker(parameter)
	{
		alert(parameter);
	}*/