MAGICA is used through a front-end, which is a separate operating system process that builds a Mathematica representation of an input MATLAB program. The front-end transfers the representation to MAGICA for type analysis; the type inferences that MAGICA generates are transferred back, for use in type-related optimizations, code generation or simply for code annotation and visualization. Exchanges between the front-end and MAGICA happen across an interprocess communication link using the MathLink protocol. The figure below shows three existing front-ends to MAGICA. Two of these - the GUI-based notebook and the text-based interface - are shipped with Mathematica. Interacting with MAGICA using them requires either the handcrafting of the program representations that are to be type inferred, or the availability of those representations on disk. (In[6] and In[18] in the tutorial are examples of handcrafted representations; In[46] in the same uses prefabricated representations.) The third front-end, called MAT2C, is a custom-built one that takes a MATLAB program in its native form and translates it to optimized C; it uses MAGICA as the inference engine to obtain the necessary type information. In fact, it was by using MAT2C that the M-file contexts for some of the examples in the tutorial were produced in advance. The figure below also shows the disk image of a sample M-file context.