Selecting more than one operand

An arrow returning to the left in a group of operands means that more than one can be selected, or that a single one can be repeated:

>>──┬──────────────────────┬────────────────────────────><
    ├─REPEATABLE_OPERAND_1─┤
    ├─REPEATABLE_OPERAND_2─┤
    └─<────────────────────┘