机场代码是每个航站楼的唯一标识符。

Airport codes are unique ___designators for each terminal.

他被选为这次活动的官方命名人，负责给所有奖项编号。

He was chosen as the official ___designator to assign numbers to all the awards.

每个电子元件都有一个独特的数字标识符作为区分标记。

Each electronic component has a unique numeric ___designator for identification.