joomla/com_wk1_6/admin/models/rules/greeting.php

<?php
/**
 * @package     Joomla.Administrator
 * @subpackage  com_wk1
 *
 * @copyright   Copyright (C) 2005 - 2015 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */
 
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
 
/**
 * Form Rule class for the Joomla Framework.
 */
class JFormRuleGreeting extends JFormRule
{
    /**
     * The regular expression.
     *
     * @access    protected
     * @var        string
     * @since    2.5
     */
    protected $regex = '^[^0-9]+$';
}