diff --git a/group/externallib.php b/group/externallib.php
index 45eadb3..48e62d6 100644
--- a/group/externallib.php
+++ b/group/externallib.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),
@@ -129,6 +130,7 @@ class core_group_external extends external_api {
                     'id' => new external_value(PARAM_INT, 'group record id'),
                     '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'),
                     'enrolmentkey' => new external_value(PARAM_RAW, 'group enrol secret phrase'),
@@ -165,7 +167,7 @@ class core_group_external extends external_api {
         $groups = array();
         foreach ($params['groupids'] as $groupid) {
             // validate params
-            $group = groups_get_group($groupid, 'id, courseid, name, description, descriptionformat, enrolmentkey', MUST_EXIST);
+            $group = groups_get_group($groupid, 'id, courseid, name, idnumber, description, descriptionformat, enrolmentkey', MUST_EXIST);
 
             // now security checks
             $context = context_course::instance($group->courseid, IGNORE_MISSING);
@@ -202,6 +204,7 @@ class core_group_external extends external_api {
                     'id' => new external_value(PARAM_INT, 'group record id'),
                     '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'),
                     'enrolmentkey' => new external_value(PARAM_RAW, 'group enrol secret phrase'),
@@ -247,7 +250,7 @@ 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.name, g.idnumber, g.description, g.descriptionformat, g.enrolmentkey');
 
         $groups = array();
         foreach ($gs as $group) {
@@ -273,6 +276,7 @@ class core_group_external extends external_api {
                     'id' => new external_value(PARAM_INT, 'group record id'),
                     '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'),
                     'enrolmentkey' => new external_value(PARAM_RAW, 'group enrol secret phrase'),
@@ -374,7 +378,7 @@ class core_group_external extends external_api {
 
         foreach ($params['groupids'] as $groupid) {
             // validate params
-            $group = groups_get_group($groupid, 'id, courseid, name, enrolmentkey', MUST_EXIST);
+            $group = groups_get_group($groupid, 'id, courseid, name, idnumber, enrolmentkey', MUST_EXIST);
             // now security checks
             $context = context_course::instance($group->courseid, IGNORE_MISSING);
             try {
@@ -578,6 +582,7 @@ 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, 'grouping description text'),
                             'descriptionformat' => new external_format_value('description', VALUE_DEFAULT)
                         )
@@ -651,6 +656,7 @@ class core_group_external extends external_api {
                     'id' => new external_value(PARAM_INT, 'grouping record id'),
                     '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, 'grouping description text'),
                     'descriptionformat' => new external_format_value('description')
                 )
@@ -672,6 +678,7 @@ class core_group_external extends external_api {
                         array(
                             'id' => new external_value(PARAM_INT, 'id of grouping'),
                             '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, 'grouping description text'),
                             'descriptionformat' => new external_format_value('description', VALUE_DEFAULT)
                         )
@@ -817,6 +824,7 @@ class core_group_external extends external_api {
                         $context->id, 'group', 'description', $grouprecord->groupid);
                         $groups[] = array('id' => $grouprecord->groupid,
                                           'name' => $grouprecord->name,
+                                          'idnumber' => $grouprecord->idnumber,
                                           'description' => $grouprecord->description,
                                           'descriptionformat' => $grouprecord->descriptionformat,
                                           'enrolmentkey' => $grouprecord->enrolmentkey,
@@ -845,6 +853,7 @@ class core_group_external extends external_api {
                     'id' => new external_value(PARAM_INT, 'grouping record id'),
                     '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, 'grouping description text'),
                     'descriptionformat' => new external_format_value('description'),
                     'groups' => new external_multiple_structure(
@@ -853,6 +862,7 @@ class core_group_external extends external_api {
                                 'id' => new external_value(PARAM_INT, 'group record id'),
                                 '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'),
                                 'enrolmentkey' => new external_value(PARAM_RAW, 'group enrol secret phrase')
@@ -931,6 +941,7 @@ class core_group_external extends external_api {
                     'id' => new external_value(PARAM_INT, 'grouping record id'),
                     '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, 'grouping description text'),
                     'descriptionformat' => new external_format_value('description')
                 )
@@ -1253,6 +1264,7 @@ class core_group_external extends external_api {
                         array(
                             'id' => new external_value(PARAM_INT, 'group record id'),
                             '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')
                         )