function DisplayDisclaimer(url_, message)
{
  
  var default_message = "You are leaving nature.ca";
  var temp_message = "" + message;
  
  // if we are passed a message use it instead of default
  if (temp_message != "undefined")
  {
    default_message = message;
  }
  
  if (confirm(default_message))
  {
    var xpos = 0;
    var ypos = 0;
    open(url_,"NewWindow","width=750,height=450,menubar=yes,toolbar=yes,scrollbars=yes,resizable=yes,location=yes,status=yes,screenx=" + xpos + ",screeny=" + ypos + ",left=" + xpos + ",top=" + ypos)
  }
}