This paper investigates questions related to the modularity in discrete
models of biological interaction networks. We develop a theoretical framework
based on the analysis of their asymptotic dynamics. More precisely, we exhibit
formal conditions under which agents of interaction networks can be grouped
into modules. As a main result, we show that the usual decomposition in
strongly connected components fulfils the conditions of being a modular
organisation. Furthermore, we point out that our framework enables a finer
analysis providing a decomposition in elementary modules
