MOSS currently has a somewhat weird source code organization, and contains a lot of stuff that isn't actually used by MOSS; this is due to our current development environment, and should be fixed shortly. In the top-level directory of the source distribution you will find four subdirectories: moss, mach4, mach4-i386, and freebsd. moss is the directory containing the source to MOSS itself: moss/kernel contains the DOS extender kernel, and moss/libc contains the MOSS-specific parts of the C library. The other directories contain other sources needed by MOSS: mach4 and mach4-i386 contain the subset of the Flux OS toolkit used by MOSS, and freebsd contains a subset of the FreeBSD source distribution from which the MOSS C library is constructed.