Index: calculation.php
===================================================================
--- calculation.php	(revision 7079)
+++ calculation.php	(working copy)
@@ -29,8 +29,9 @@
 if ($section !== 'calculation') {
     $url->param('section', $section);
 }
-if ($idnumbers !== null) {
-    $url->param('idnumbers', $idnumbers);
+if ($idnumbers !== null && is_array($idnumbers)) {
+    foreach($idnumbers as $k => $v)
+        $url->param('idnumber_'.$k, $v);
 }
 $PAGE->set_url($url);
 
@@ -76,6 +77,8 @@
 
 } elseif (!empty($section) AND $section='idnumbers' AND !empty($idnumbers)) { // Handle idnumbers separately (non-mform)
     //first validate and store the new idnumbers
+
+    
     foreach ($idnumbers as $giid => $value) {
         if ($gi = grade_item::fetch(array('id' => $giid))) {
             if ($gi->itemtype == 'mod') {