In what way can multiplicity be represented in structural diagrams?

Multiplicity in structural diagrams is effectively represented as brackets or in the top right corner of rectangles. This method provides a clear visual indication of the number of instances of a classifier that are allowed in a relationship. In UML (Unified Modeling Language) diagrams, multiplicity is shown to quantify the relationships between different entities, such as classes or components, allowing modelers to specify how many instances of one element can associate with instances of another.

Using brackets, for example, allows for straightforward notations like [0..], [1..1], or [1..], which denote the range of possible instances in a relationship. This visual representation is integral to understanding model relationships quickly and conveys the necessary information without requiring additional explanation.

In contrast, showing multiplicity only in the center of blocks, as suggested in some choices, would not provide the clarity needed for distinguishing relationships. Similarly, annotation outside the diagram or relying solely on legend explanations may complicate interpretation and could detract from the immediacy and efficiency of understanding the model design. Thus, using brackets or positioning multiplicity indicators on the rectangles is the preferred and standard way to depict these concepts in structural diagrams.