diff --git a/src/Mod/Fem/femtaskpanels/task_material_common.py b/src/Mod/Fem/femtaskpanels/task_material_common.py
index fba2135c50..49b1cb82ec 100644
--- a/src/Mod/Fem/femtaskpanels/task_material_common.py
+++ b/src/Mod/Fem/femtaskpanels/task_material_common.py
@@ -138,6 +138,8 @@ class _TaskPanel:
         self.toggleInputFieldsReadOnly()
 
         # hide some groupBox according to material category
+        # note: input_fd_vol_expansion_coefficient is currently not used
+        #       it might be used in future for solids 
         self.parameterWidget.label_category.setText(self.obj.Category)
         if self.obj.Category == "Fluid":
             self.parameterWidget.groupBox_mechanical.setVisible(0)