<p>In building an object-oriented system, we can characterize an object's dynamic nature by modeling its roles. But some modeling abstractions represent roles without addressing the relationships among them. The Cascade pattern, which represents layered and ordered whole-part relationships between objects, solves this problem. The authors' examples from a public transportation system demonstrate how important this precision can be.</p>

Liping Zhao, Ted Foster, "Modeling Roles with Cascade", IEEE Software, vol. 16, no. , pp. 86-93, September/October 1999, doi:10.1109/52.795106