How many operands can an opt operator have at most?

The opt operator in modeling contexts typically represents an optional behavior or element within a system diagram. By its nature, the opt operator is designed to express a condition where some actions or entities may or may not occur. This operator is usually applied to a single operand, which reflects that the optionality pertains to a specific scenario or action.

When you think of the structure of the opt operator, it essentially represents a case where either the operand is executed (the action occurs) or it is ignored (the action does not occur). This clear binary choice inherently limits it to one operand. Therefore, the understanding of the operational logic behind the opt operator clearly indicates that it can handle only one operand at a time, signifying that its design was intended for singular optionality. This aligns with the fundamental principles of systems modeling where clarity and distinctness in expressions are paramount.