The Uni ed Modeling Language (UML) currently proposes a mechanism to model recurrent design structures: the parameterized collaborations. The main goal of this mechanism is to model the struc- ture of Design Patterns. This is an interesting feature because it can help designers to point out pattern application without spending time with intricate design details. Moreover, it can also help designers to better document their systems and to manage their own design pattern library, which could be used in di erent systems or projects. However, from a tool perspective, the semantics associated to parameterized collaborations is still vague. To put it more precisely, the underlying representation of a design pattern and of its application, and the binding between these two levels is not exactly de ned, and therefore, can be interpreted in di erent ways. This article has two purposes. First, we point out ambiguities and clarify some misunderstanding points concerning parameterized colla- borations in the \o cial" UML literature. We also show the limits of this mechanism when e ectively modeling design patterns. Second, we propose some workarounds for these limits and describe how a tool inte- grating this mechanism could help with the semi-automatic application of design patterns.