What is the visual representation of operands in a combined fragment?

The visual representation of operands in a combined fragment is represented by horizontal dashed lines. In Unified Modeling Language (UML) sequence diagrams, combined fragments are used to represent constructs that combine multiple interactions. Specifically, operands within a combined fragment serve to define segments of the interaction that are governed by specific conditions or loops.

The horizontal dashed lines effectively delineate the boundaries of each operand, making it clear where one segment of interaction ends and another begins. This visual cue enhances the clarity of the sequence diagram, allowing viewers to instantly recognize the flow of the interactions as they relate to the conditions specified within the combined fragment. Each operand can contain its own sequence of messages, and the use of dashed lines contributes to the overall structural integrity of the diagram, facilitating easier comprehension of the sequences being portrayed.