The Fortran M compiler, fm, is a preprocessor rather than a true compiler. However, it is capable of compiling and linking Fortran M files (.fm suffix), Fortran M files with C preprocessor (CPP) directives (.FM suffix), Fortran files (.f suffix), Fortran files with CPP directives (.F suffix), and C files (.c suffix).
Every effort was made to make the Fortran M compiler conform to conventions used by most other compilers. Exceptions and additions are described in the following sections.