The term "Members Discount" did not really explain the discount that I needed for my store. So I altered this small file and changed "Members Discount" to "Preferred Customer Discount".
In catalog/includes/language/english/modules/order_total/
Change ot_xmembers.php to this:
<?php
/*
$Id: ot_gv.php,v 1.0 2002/04/03 23:09:49 hpdl Exp $
osCommerce, Open Source E-Commerce Solutions
http://www.oscommerce.com
Copyright © 2002 osCommerce
Released under the GNU General Public License
*/
define('MODULE_XMEMBERS_TITLE', 'Preferred Customer Discount');
define('MODULE_XMEMBERS_DESCRIPTION', 'Preferred Customer Discount');
define('SHIPPING_NOT_INCLUDED', ' [shipping not included]');
define('TAX_NOT_INCLUDED', ' [Tax not included]');
?>
Now it shows up as "Preferred Customer Discount" in check-out rather than "Members Discount".