This is the level most often used in MODULEF, consisting of activating one processor after the other (chaining processors).
In practice, activating a processor corresponds to executing a program in two steps: in the first step the data is generated interactively; in the second step the computation is performed, without intervention by the user.
Each processor performs one well-determined task, for example, mesh construction, specification of boundary conditions, finding the solution to a system of linear equations, etc.