C macros are indicated by the structured comment /*M ... M*/.
Unlike the case of C routines, macro definitions do not provide any
information on the types of the arguments.
Thus, the body of a structured comment
for a C macro
should include a synopsis section, containing a declaration of the
macro as if it were a C routine. For example, if the Swap example were
implemented as a macro, the structured comment for it would look like
/*M Swap - Swaps two pointersIt is important that the word Synopsis be used; doctext and related programs (bfort and doc2lt) use this name to find the C-like declaration for the macro.
Parameters: . ptr1,ptr2 - Pointers to swap
Synopsis: void Swap( ptr1, ptr2 ) void **ptr1, **ptr2; M*/