diff --git a/DDG4/plugins/Geant4SDActions.cpp b/DDG4/plugins/Geant4SDActions.cpp
index 0a5e888a6a3c261a5fb4004cfefbca410b0348e5..1f7532115a8cd6703dcf1e624051c4957b3f5e67 100644
--- a/DDG4/plugins/Geant4SDActions.cpp
+++ b/DDG4/plugins/Geant4SDActions.cpp
@@ -29,6 +29,16 @@ namespace DD4hep {
     // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     //               Geant4SensitiveAction<Geant4Tracker>
     // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+    /** \addtogroup Geant4SDActionPlugin
+     *
+     * @{
+     * \package Geant4TrackerAction
+     *
+     * \brief Sensitive detector meant for tracking detectors, will produce one hit per step
+
+     *
+     * @}
+     */
 
     /// Define collections created by this sensitivie action object
     template <> void Geant4SensitiveAction<Geant4Tracker>::defineCollections() {
@@ -75,6 +85,16 @@ namespace DD4hep {
     // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     //               Geant4SensitiveAction<Calorimeter>
     // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+    /** \addtogroup Geant4SDActionPlugin
+     *
+     * @{
+     * \package Geant4CalorimeterAction
+     *
+     * \brief Sensitive detector meant for calorimeters
+
+     *
+     * @}
+     */
 
     /// Define collections created by this sensitivie action object
     template <> void Geant4SensitiveAction<Geant4Calorimeter>::defineCollections() {
@@ -138,6 +158,16 @@ namespace DD4hep {
      *  \author  M.Frank
      *  \version 1.0
      *  \ingroup DD4HEP_SIMULATION
+     
+     * \addtogroup Geant4SDActionPlugin
+     *
+     * @{
+     * \package Geant4OpticalCalorimeterAction
+     *
+     * \brief Sensitive detector meant for optical calorimeters
+
+     *
+     * @}
      */
     struct Geant4OpticalCalorimeter {};
 
@@ -187,6 +217,20 @@ namespace DD4hep {
     //               For scintillator with Geant4 BirksLaw effect
     // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
+
+    /** \addtogroup Geant4SDActionPlugin
+     *
+     * @{
+     * \package Geant4ScintillatorCalorimeterAction
+     *
+     * \brief Sensitive detector meant for scintillator calorimeters
+
+     This sensitive action will apply Birks' law to the energy deposits
+
+     *
+     * @}
+     */
+
     struct Geant4ScintillatorCalorimeter {};
 
     /// Define collections created by this sensitivie action object
@@ -251,6 +295,21 @@ namespace DD4hep {
      *  \version 1.0
      *  \ingroup DD4HEP_SIMULATION
      */
+
+    /** \addtogroup Geant4SDActionPlugin
+     *
+     * @{
+     * \package Geant4TrackerCombineAction
+     *
+     * \brief Sensitive detector meant for tracking detectors will combine
+     * multiple steps of the same track in the same sensitive volume into a
+     * single hit
+
+     *
+     * @}
+     */
+
+
     struct TrackerCombine {
       typedef Geant4HitCollection HitCollection;
       Geant4Tracker::Hit  pre, post;
diff --git a/DDG4/plugins/Geant4TrackerWeightedSD.cpp b/DDG4/plugins/Geant4TrackerWeightedSD.cpp
index aeaed40d86e45468ae9833b5b7c99bac5747f2bd..7877361162d218f9bed97de82b6d318514649024 100644
--- a/DDG4/plugins/Geant4TrackerWeightedSD.cpp
+++ b/DDG4/plugins/Geant4TrackerWeightedSD.cpp
@@ -44,6 +44,29 @@ namespace DD4hep {
      *  \version 1.0
      *  \ingroup DD4HEP_SIMULATION
      */
+
+    /** \addtogroup Geant4SDActionPlugin
+     *
+     * @{
+     * \package Geant4TrackerWeightedAction
+     *
+     * \brief Sensitive detector meant for tracking detectors with multiple ways to combine steps
+
+     
+      \param integer HitPositionCombination
+        -# Use energy weights to define the position of the energy deposit
+        -# Set the hit position between the step pre and post point
+        -# Set the hit position to the position of the step pre point
+        -# Set the hit position to the position of the step post point
+
+      \param bool CollectSingleDeposits
+        - If true each step is written out
+
+
+     *
+     * @}
+     */
+
     struct TrackerWeighted {
       typedef Geant4HitCollection HitCollection;