Trk::TrackTruthCollection_p2::Entry Node1 Trk::TrackTruthCollection _p2::Entry + index + probability Node2 HepMcParticleLink_p2 # m_mcEvtIndex # m_evtColl + HepMcParticleLink_p2() + HepMcParticleLink_p2() Node2->Node1 +particle Node3 long Node3->Node2 #m_barcode