+//----------------------------------------------------------------------------
+// helper functions for script execution control
+//
+function processing_start()
+{
+ processing_end();
+ $_SESSION['Processing'] = $_SERVER['PHP_SELF'];
+}
+
+function processing_end()
+{
+ unset($_SESSION['Processing']);
+ if ( isset($_SESSION['Items']) ) {
+ unset($_SESSION['Items']->line_items);
+ unset($_SESSION['Items']);
+ }
+}
+
+function processing_active()
+{
+ return (isset($_SESSION['Processing']) && $_SESSION['Processing']==$_SERVER['PHP_SELF']);
+}
+