G4UA::StepNtupleTool Node1 G4UA::StepNtupleTool + StepNtupleTool() # makeAndFillAction() Node2 G4UA::UserActionToolBase < StepNtuple > # m_actions + UserActionToolBase() + fillUserAction() # makeAndFillAction() Node2->Node1 Node3 extends< AthAlgTool, IUserActionTool > Node3->Node2