Some of the functions provided in the minimal C library depend on lower level I/O routines in the POSIX library (see Section 13) to provide mappings to the appropriate OSKit COM interfaces. For example, fopen in the C library will chain to open in the POSIX library, which in turn will chain to the appropriate oskit_dir and oskit_file COM operations. Certain initialization routines in the POSIX library may need to be called; refer to Section 13.3 for details.