function button(zap) 
		{ 
   			if (document.getElementById) 
			{ 
   				var div = document.getElementById(zap).style; 
    			if (div.display == "block") 
				{ 
    				div.display = "none"; 
    			} 
				else 
				{ 
    				div.display = "block"; 
   				} 
   				
				return false; 
   			} 
			else 
			{ 
   				return true; 
  			} 
  		} 
		
		function bookmark(url, description) 
		{
		  var netscape="Firefox gebruikers: CTRL+D om het toe te voegen.";
		  if (navigator.appName=='Microsoft Internet Explorer'){
			window.external.AddFavorite(url, description); 
		  } else { 
			alert(netscape); 
		  }
		}