diff --git a/typo3/sysext/core/Classes/Utility/ExtensionManagementUtility.php b/typo3/sysext/core/Classes/Utility/ExtensionManagementUtility.php
index 49b0e58553b43a4d1820919b86c12dd2e2fd8915..2c3ca40d4e000fd33263f6b34b4e8ced4bff6731 100644
--- a/typo3/sysext/core/Classes/Utility/ExtensionManagementUtility.php
+++ b/typo3/sysext/core/Classes/Utility/ExtensionManagementUtility.php
@@ -424,6 +424,9 @@ class ExtensionManagementUtility
      * - $relativeToField = mailform
      * - $relativePosition = after
      *
+     * $item has an optional fourth parameter for the groupId (string), to attach the
+     * new item to. The groupname is defined when a group is added with addTcaSelectItemGroup
+     *
      * @throws \InvalidArgumentException If given parameters are not of correct
      * @throws \RuntimeException If reference to related position fields can not
      * @param string $table Name of TCA table