diff --git a/group/externallib.php b/group/externallib.php
index 45eadb3..f14167f 100644
--- a/group/externallib.php
+++ b/group/externallib-MOD.php
@@ -51,6 +51,7 @@ class core_group_external extends external_api {
                         array(
                             'courseid' => new external_value(PARAM_INT, 'id of course'),
                             'name' => new external_value(PARAM_TEXT, 'multilang compatible name, course unique'),
+                            'idnumber' => new external_value(PARAM_RAW, 'id number', VALUE_OPTIONAL),
                             'description' => new external_value(PARAM_RAW, 'group description text'),
                             'descriptionformat' => new external_format_value('description', VALUE_DEFAULT),
                             'enrolmentkey' => new external_value(PARAM_RAW, 'group enrol secret phrase', VALUE_OPTIONAL),
@@ -247,7 +248,7 @@ class core_group_external extends external_api {
         require_capability('moodle/course:managegroups', $context);
 
         $gs = groups_get_all_groups($params['courseid'], 0, 0,
-            'g.id, g.courseid, g.name, g.description, g.descriptionformat, g.enrolmentkey');
+            'g.id, g.courseid, g.idnumber, g.name, g.description, g.descriptionformat, g.enrolmentkey');
 
         $groups = array();
         foreach ($gs as $group) {
@@ -272,6 +273,7 @@ class core_group_external extends external_api {
                 array(
                     'id' => new external_value(PARAM_INT, 'group record id'),
                     'courseid' => new external_value(PARAM_INT, 'id of course'),
+                    'idnumber' => new external_value(PARAM_RAW, 'id number', VALUE_OPTIONAL),
                     'name' => new external_value(PARAM_TEXT, 'multilang compatible name, course unique'),
                     'description' => new external_value(PARAM_RAW, 'group description text'),
                     'descriptionformat' => new external_format_value('description'),