Class Structure don't show one of list by identity

Hi ItemType 【Class Structure】 I add three item AAA、BBB、CCC. I create two Identity -->Identity_A  、Identity_B. When Identity_A  login and  click classification show list,I want  list just show  AAA 、BBB 2 item. When Identity_B login and  click classification show list, I want list  just show BBB、CCC item. How can to setting or write method control. I don't know where event can I use.