Writing processes are multiple and focus on different kinds of knowledge and representation (domain, linguistic and pragmatic). This multiplicity needs, as seen in Chapter 4, the implementation of management, control and regulation of processing. Defined as a complex activity, the text writing assumes that the writer could manage a great number of constraints (Flower and Hayes, 1980; Scardamalia, 1981). In addition, the choice of a given strategy (added to the simultaneous consideration of this set of constraints) supposes the management of various processing levels (Graham and Harris, 1996). Thus, one of the fundamental problems of language production consists in the capacity to manage simultaneously and/or serially different types of processing, while taking into account Working Memory limited capacity (Bereiter and Scardamalia, 1984; Glynn, Britton, Muth and Dogan, 1982).