diff --git a/Classes/DataHandling/FrontendEditDataHandler.php b/Classes/DataHandling/FrontendEditDataHandler.php
index b466c06..f40a8d1 100644
--- a/Classes/DataHandling/FrontendEditDataHandler.php
+++ b/Classes/DataHandling/FrontendEditDataHandler.php
@@ -28,6 +28,8 @@ use TYPO3\CMS\Frontend\View\AdminPanelView;
 
 /**
  * Calls DataHandler and stores data
+ *
+ * @internal this is a concrete TYPO3 implementation and solely used for EXT:feedit and not part of TYPO3's Core API.
  */
 class FrontendEditDataHandler
 {
diff --git a/Classes/FrontendEditPanel.php b/Classes/FrontendEditPanel.php
index 1fb3532..e79ed21 100644
--- a/Classes/FrontendEditPanel.php
+++ b/Classes/FrontendEditPanel.php
@@ -26,6 +26,8 @@ use TYPO3\CMS\Frontend\Controller\TypoScriptFrontendController;
 
 /**
  * View class for the edit panels in frontend editing.
+ *
+ * @internal this is a concrete TYPO3 implementation and solely used for EXT:feedit and not part of TYPO3's Core API.
  */
 class FrontendEditPanel
 {
diff --git a/Classes/Middleware/FrontendEditInitiator.php b/Classes/Middleware/FrontendEditInitiator.php
index 8c0b77b..e450c43 100644
--- a/Classes/Middleware/FrontendEditInitiator.php
+++ b/Classes/Middleware/FrontendEditInitiator.php
@@ -27,6 +27,8 @@ use TYPO3\CMS\Frontend\Controller\TypoScriptFrontendController;
 
 /**
  * PSR-15 middleware initializing frontend editing
+ *
+ * @internal this is a concrete TYPO3 implementation and solely used for EXT:feedit and not part of TYPO3's Core API.
  */
 class FrontendEditInitiator implements MiddlewareInterface
 {