The processors mentioned above are in fact merely a succession of calls to the various modules. This flexibility, which is particularly important for research and development, is an important feature of the MODULEF software.
If certain functions are not available, it is up to the user to modify an existing processor him/herself, or even create a new processor consisting of calling some modules (section below).
For a user who wishes to call some modules, MODULEF resembles a classic library of Fortran subroutines.
A module is a set of procedures performing one logical process or calculation step. The modules communicate with each other through data structures (D.S.), where a data structure is a set of arrays containing the result corresponding to a computational step. Therefore, a module transforms an input data structure (I.D.S.) into an output data structure (O.D.S.). For example,