function val_shipping_address(x,set_focus) {
  w_shipping_address = x.value.toUpperCase();
  if (set_focus && set_focus != null)
  	var w_set_focus = set_focus;
  else
    var w_set_focus = 'Y';
	
  if(w_shipping_address.indexOf('PO ') >= 0 || w_shipping_address.indexOf('P.O.') >= 0 || w_shipping_address.indexOf('P. O.') >= 0 || w_shipping_address.indexOf('POB') == 0 || w_shipping_address.indexOf('BOX') == 0 || w_shipping_address.indexOf('P O BOX') >= 0 ){
		alert('PO Boxes are not valid for shipping addresses.')
		if(w_set_focus == 'Y'){
			x.focus();
		}
		return false;
  }
  return true;
}