SiCellId Node1 SiCellId - m_word + SiCellId() + SiCellId() + SiCellId() + etaIndex() + phiIndex() + strip() + isValid() + operator==() + operator!=() + operator<() + word() Node2 InDetDD::SiReadoutCellId   + SiReadoutCellId() + SiReadoutCellId() + SiReadoutCellId() Node1->Node2