function external()
{
	if (document.getElementsByTagName)
	{
  	var i, a;
  	a = document.getElementsByTagName('a');
  	for (i in a)
		{
   		if (a[i].getAttribute('href') && a[i].getAttribute('rel') == 'external')
				a[i].target = '_blank';
		}
	}
}

window.onload = external;