  In a multi-modeling based approach, the system under development is described
by several models that represent various perspectives and concerns. Obviously,
these partial representations are less complex than the global model, but they
need to be composed to address validation and synchronization tasks. The model
composition is a crucial model driven development operation, but it remains a
tedious and error prone activity. In this perspective, a traceability mechanism
offers a way to master this complexity by providing support to comprehend the
composition effects. In previous work, we presented a traceability approach
dedicated to this operation. The current takes advantages of these experiments,
and proposes a formalization of the model composition traceability. Also, an
overview of a generic traceability approach is provided. The latter relies on
the formal definition we introduce for the model composition operation and the
related traces.
