The system consists of six lines named M1, M2, M3, M4, M5 and the M6 Mini-Metro. More lines are under construction or planned: M8 (Bostancı-Dudullu) will be on the Asian side, while M7 (Kabataş-Mahmutbey), M9 (Ataköy-İkitelli) will be on the European side.[4]