<?php defined('SYSPATH') or die('No direct access allowed.'); /** * This interface ensures that all items have the required invoice methods * * @package Invoice * @category Interface * @author Deon George * @copyright (c) 2009-2013 Open Source Billing * @license http://dev.osbill.net/license.html */ interface Invoicable { // Render an invoice line item. public function invoice_item($item_type); } ?>